This study investigated the anisotropic pullout behavior of dry bauxite slag-geogrid interfaces to address a critical knowledge gap in abandoned bauxite slag deposits reinforcement. Laboratory tests were conducted on coarse sand (slag of 2.5-4.75 mm) and fine gravel (slag of 10-12 mm) using biaxial (SS40) and triaxial (TX150) geogrids across 0°, 22.5°, 45°, 67.5° and 90° by the self-developed pullout apparatus that provide a new test method under normal stresses of 20-60 kPa. Results revealed that the slag-geogrid interface pullout strength increases with increasing normal stress. A new parameter η was proposed that representing the magnitude of pullout strength anisotropy and was defined as the difference between the maximum and minimum pullout strength divided by the average pullout strength across orientations. It exhibited values of 0.47-1.36 across tested conditions, with this anisotropy diminishing significantly as normal stress increased to 60 kPa. Fine gravel-geogrid interfaces showed higher peak η values than coarse sand counterparts. The interface pullout strength of bauxite slag-SS40 and bauxite slag-TX150 disparity amplified with increasing normal stress. The rectangular mesh of SS40 increased normal stress sensitivity compared to TX150's stable triangular structure. Results demonstrated that design approaches assuming η = 0 neglect directional effects, potentially explaining recurrent geogrid-reinforced structure failures. This research provided essential data for optimizing geosynthetics reinforcement slag deposit under complex stress orientations.

Soluble salts in soil cause changes in soil behaviour, the extent of which varies depending on salinity levels. Salt-induced soil deformation leads to various engineering problems. Na2SO4 is among the most widespread and influential salts. This study focuses on Na2SO4 and investigates its effects on soil strength via a series of triaxial tests performed in the laboratory. The study examines different levels of salt and moisture content. Additionally, the study investigated the soil mechanism through its meso and micro structure. The research indicates that the impact of salinity on soil strength is modulated by moisture content. In situations where moisture content is low, salinity markedly affects the soil strength; however, as moisture content increases, the impact of salinity on soil strength decreases. Salinity alters the shape, size and orientation of soil particles, resulting in modifications to the interparticle and charge forces. This ultimately leads to changes in the soil strength parameters.

This paper studies the finite-time stability (FTS) for stochastic impulsive systems (SIS). The notions of FTS including GKL$$ \mathcal{GKL} $$-FTS and event-GKL$$ \mathcal{GKL} $$-FTS are proposed for SIS. The comparison principles for GKL$$ \mathcal{GKL} $$-FTS and event-GKL$$ \mathcal{GKL} $$-FTS are established, respectively. Then the FTS criteria with the settling time estimates are derived. The criteria of GKL$$ \mathcal{GKL} $$-FTS and event-GKL$$ \mathcal{GKL} $$-FTS relax the requirements on stabilizing flow and jump for FTS in the literature. Finally, two examples are presented to demonstrate the obtained results.

When a tunnel crosses a landslide orthogonally, this interaction can easily lead to instability in both the landslide and tunnel structures. Based on the relative positional relationship between a landslide and a tunnel, we studied the stress mode and deformation characteristics of the tunnel in three positional relationships: within the landslide mass, the sliding surface, and the sliding bed. The tunnel is a typical type located on a sliding surface at an engineering site, so we established a numerical model showing the intersection of the tunnel and the sliding surface. The plastic zone distribution, stress characteristics, and displacement distribution characteristics of the surrounding rock before and after tunnel excavation were studied. Based on the simulation results, we analyzed the control effect of anti-slide piles in controlling the tunnel’s deformation in the surrounding rock from four perspectives: the arrangement of anti-slide piles, the spacing between piles and tunnels, the diameter of anti-slide piles, and the depth of piles embedded in the bedrock. By analyzing the deformation law of the landslide mass and the force characteristics of the tunnel structure under the orthogonal conditions of a tunnel landslide, we provide theoretical guidance for the adoption of anti-slide piles to control instability in tunnel structures.

This paper studies the finite-time stability via GKL-functions (GKL-FTS) for impulsive dynamical systems (IDS). The notions of GKL-functions, GKL-FTS, and event-GKL-FTS are proposed for IDS. The GKL-FTS is a type of well-defined finite-time stability which is expressed via GKL-functions. The GKL-FTS is decomposed into specific types through the decomposition of GKL-functions. By establishing the comparison principles of FTS including GKL-FTS and event-GKL-FTS, and by using the decompositions of GKL-functions, the criteria on GKL-FTS and event-GKL-FTS are derived for IDS. And with the help of the decompositions of GKL-FTS, the settling time of the GKL-FTS is effectively calculated. Moreover, two types of specific GKL-FTS with fixed settling time, i.e., GKL-FTS via resetting state to zero, and event-GKL-FTS via Zeno behaviour, are provided. And four examples with numerical simulations are presented to demonstrate the effectiveness of the results. It is shown that the GKL-FTS criteria are less conservative in relaxing the FTS conditions of IDS in the literature. And specific effects of impulses on FTS are given in these GKL-FTS criteria, including that an unstable continuous system may obtain FTS under a finite number of impulses.

夯沉量是评价处治效果的重要指标,为深入分析煤矸石等复杂成分的杂填场地高能级强夯的变化规律,以离隰高速公路某杂填场地高能级强夯处治工程为研究对象,对三个不同杂填场地进行了高能级强夯试验研究,对不同夯击遍数的各个夯坑深度、几何参数和夯点累计夯沉量进行了分析.基于体积等效原理,考虑了不同夯击能和杂填物质组成,建立了单个夯坑模型-场地夯沉量预测模型.研究结果表明,用实测数据可解释高能级强夯采用分遍、不同能级和不同夯点间距组合的实际意义.各遍夯击对场地的压缩功效排序为:第 1遍主夯>第 4遍加固夯>满夯>第2遍主夯、第3遍插夯.研究成果可为同类工程提供理论和实践借鉴.

There are a large number of structural planes distributed in the surrounding rock of a tunnel, and this is one of the key factors causing a tunnel’s instability. Due to different geological and historical conditions, the distribution characteristics and the occurrence of structural planes in the rock mass also have significant differences. In engineering, it is common to encounter structural planes that cut across the tunnel section and have a significant impact on the stability. The occurrence of structural planes is a key factor controlling the mechanical behavior of the surrounding rock. Based on this, laboratory uniaxial compression tests were carried out by constructing a small tunnel physical model with single structural planes of different inclination angles. A related numerical simulation analysis was also carried out. This research indicates that: (1) Under the influence of a single structural plane, the dip direction with 30°–60° is the most dangerous situation, and when the dip angle of the structural plane is between 38 and 88°, it will slip along the structural plane. (2) According to the mechanical mechanism, there are three types of cracks: tensile cracks, shear cracks, and tensile shear cracks. According to the deformation characteristics, there are four types: tension, friction, bending, and shear. (3) There is a certain correlation between the strength of a single discontinuity rock mass and that of a multi-jointed rock mass. When the dip angle of the joints’ combination is 45°+60°, the rock mass is in its weakest state.

Abstract Rockfall disasters are widely developed along highways in Tai-hang Mountains. The rockfall is difficult to predict effectively because of its sudden, which brings great threat to traffic. Therefore, it is of great significance to assess the susceptibility of rockfall areas and the hazard of rockfall. The Tai-hang Mountains highways along the high and steep rock slope were regarded as the object in this paper, 267 rockfall points had been obtained through field investigation from 2020–2022. And the susceptibility of rockfall was conducted according to the topography, geomorphology, lithology, river, and structure. On this basis, the rockfall susceptibility method based on the survey data has been put forward. The tendency of rockfall along the highway in Tai-hang Mountains was conducted by this method. The research results have reference significance for the evaluation of rockfall disasters in mountainous areas, and can provide a basis for rockfall prevention.

This paper studies the stability for impulsive dynamical networks (IDN) where different nodes may have different impulse time sequences. By deriving the conditions of global uniform exponential stability for zero-order delayed systems, the criteria of stability for IDN are established. The stability results for IDN are then used to design event-triggered impulsive control (ETIC) for stabilization of continuous-time dynamical networks (CDN). In every node of CDN, three levels of event-triggering conditions are set for ETIC. The ex-ponential stabilization of CDN is shown to be achieved by the designed ETIC and it also shows that the ETIC is robust w.r.t. time-delays. Moreover, a non-instantaneous ETIC (NI-ETIC) is proposed for the stabilization of CDN. Three examples with numerical simulations are given to show that the designed ETIC has lower impulse frequency and cost of control than the classic time-triggered impulsive control. It is also shown that the discontinuity and the instantanity of ETIC are improved by the NI-ETIC.(c) 2023 Elsevier Inc. All rights reserved.

This paper studies the problem of the state estimate of a class of DC microgrids with both disturbed states and disturbed outputs via event-triggered impulsive observer (ETIO). First, a mathematical model is established for such class of DC microgrids, and then the notion of impulsive observer including impulsive observer with K-asymptotic gain is proposed. Then, by using two Lyapunov-like functions, a scheme of event-triggered impulsive control (ETIC) via three layers of event-triggering conditions is designed for ETIO to track the state of the DC microgrid. And an algorithm is given for the implementation of ETIC in practice. The ETIC scheme is then extended to the sampling-based ETIC (S-ETIC) to reduce the calculation and improve the effectiveness of the ETIC. Both theoretical proofs and numerical simulations are given to show that the proposed ETIO via both ETIC and S-ETIC can track the state of the DC microgrid within K-asymptotic gain. Specifically, when the disturbance tends to zero, the tracking is accurate. Moreover, the simulation is given for comparisons between ETIO and other observers including the classic impulsive observer, Luenberger observer, sliding mode observer, and extended state observer. It is shown that the designed ETIO has advantages of lower impulse frequency, lower control cost, and smaller tracking error than the other observers.

In view of the common phenomenon of the loess degradation and the deformation or failure of the high fill slope under the dry-wet circulation action, the model tests of loess slope under the dry-wet cycle are carried out by using the self-designed model test system, which introduces a new monitoring method based on fiber Bragg grating (FBG) sensing technology. A series of FBG sensors are attached to the surface and inside of the slope to measure the magnetostrictive strain to reveal the relationship between the deformation development, strain localization and the failure process of the slope under the action of dry and wet cycling. Therefore, it is helpful to propose the influence rules of the number and amplitude of the wet and dry cycles on the loess high fill slope.

Taking the treatment project of a miscellaneous field with the high-energy dynamic compaction in Lixi Expressway as the research objection, this paper conducted the high-energy dynamic compaction tests for three different miscellaneous fill fields. Using the empirical statistical method, the data fitting of the accumulated settlement of each pit with different tamping times was carried out, and the settlement prediction model of every single tamping pit was established. The research results showed that for the relationship between the accumulated settlement and the number of tamping, the logarithmic formula can be used to express that of shallow tamping pits, which can be normalized to a linear formula, while the exponential formula can be used to express that of deep tamping pits, which can be normalized to a cubic polynomial formula. Relevant formulas can be used for the settlement prediction of similar sites.

In July 2019, a landslide occurred in Xiangning County, located in the southwest of Shanxi Province on the Loess Plateau. The moisture content, cohesion, and internal friction angle of soil at different depths of the landslide were obtained by an in situ trench test. It was found that the sliding zone of the landslide was located at a depth of 3 m. In addition, the field monitoring results indicate that before the landslide occurs, the surface soil is continuously deformed, while the deep soil is not deformed. What is more, the slope is strongly affected by rainfall and temperature. In order to further study the influence of rainfall and temperature on loess landslides, the laboratory dry–wet cycle model tests under different rainfall conditions were carried out on loess slope with different slopes. Research indicates that (1) the dry–wet alternation mainly occurs at the shoulder of the slope surface, accompanied by a large number of small cracks. The soil of slope shoulder and toe is tensioned and deformed toward to free face, while the medium soil is compressed. (2) The deformation of the gentle slope is obvious in the early stage of the dry–wet cycle, while the deformation of the steep slope mainly occurs in the late stage of the dry–wet cycle. It is prone to shallow collapse and mudflow on the gentle slope, and collapse and deep slide on the steep slope. (3) Under the influence of dry–wet cycles, the deformation of loess gradually develops from surface to deep and presents four states: shell state, saturated state, unsaturated state, and loose state. Its essence is the change of soil particles’ structure and arrangement. The research results can provide a theoretical basis for slope deformation prediction and deformation control in the loess region.

In this paper, based on the high-energy dynamic compaction project in a miscellaneous fill field in Lixi Expressway, the limits of average compaction subsidence of the last two times of tamping of three high-energy dynamic compactions were analyzed by field tests, and the standard of stopping tamping fitting to this project was proposed. The results show that due to the complex composition and poor uniformity of the miscellaneous fill field, it is advisable to use the average compaction subsidence of the last two compactions as the main control index to stop tamping. In this case, the average compaction subsidence of three energy levels of 12 000 kN·m, 16 000 kN·m, and 25 000 kN·m were 25 cm, 30 cm, and 35 cm, respectively. The standard of stopping tamping proposed in this paper can provide a basis for revising similar engineering and dynamic compaction standard.

This paper studies the input-to-state stability (ISS) for time-varying delayed systems (TVDS) in Halanay-type inequality forms. The time-delay in TVDS is allowed to be time-varying and unbounded. By introducing the notion of a uniform M-matrix, exponential ISS theorems are established respectively for continuous-time, discrete-time, and zero-order TVDS. The convergence rates of exponential ISS and ISS gains and their relation are subsequently estimated. These ISS theorems are less conservative and generalize the results of stability and ISS for Halanay-type inequalities in the literature. Moreover, necessary conditions of ISS are given for TVDS in Halanay-type equality forms. By specializing the ISS results to linear time-invariant delayed systems, the necessary and sufficient conditions of ISS are derived respectively. Three examples are given throughout the paper to illustrate the theoretical results.

This paper investigates the input-to-state contraction for impulsive systems. The notion of input-to-state contraction (ISC) is proposed via incremental input-to-state stability (δISS). By using the method of variation, the equivalence between global ISC and exponential δISS is established. Then by the technique of the average dwell-time (ADT), some criteria for global ISC and exponential δISS are derived for impulsive systems. Moreover, by using impulse frequency (I.F.) to replace ADT, the criteria are improved and less conservative criteria via I.F. are established for global ISC and exponential δISS. The criteria are used to derive global ISC and exponential δISS for continuous and discrete time systems. Discussions are given to relax the differentiable vector fields. And the criteria of exponential δISS via the Lyapunov-like function are derived for impulsive systems satisfying time-varying Lipschitz condition. Finally, three examples are worked out for illustrations, where impulsive control is designed for chaotic systems to achieve global ISC.

黄土边坡在遭受反复降雨-日照作用时,边坡坡表会发生剥落滑塌,导致坡体稳定性降低,且坡率不同对稳定性影响也不同.以不同坡率非对称黄土边坡为研究对象,采用模型试验方法模拟了干湿循环条件下边坡的变形破坏过程,探究了干湿循环下非对称边坡的变形响应特征及破坏模式.研究结果表明:非对称边坡在干湿循环累积效应下呈现不同的变形特征.缓坡变形早于陡坡,变形速率小于陡坡,缓坡破坏表现形式为小范围坡表剥落和整体牵引式缓慢滑移.陡坡破坏表现形式为坡顶和坡面裂缝发展,贯通,突发局部崩塌.黄土边坡设计时不仅要考虑综合坡率,还要考虑缓坡率带来的干湿循环坡表劣化问题,加强坡面防护.

By combining model testing and numerical simulation, this paper focuses on the influence of landslides on tunnels in loess-bedrock strata by using the perfect landslide–tunnel system (LTS). A mechanical test and simulation (MTS) system was used to provide thrust for loading and unloading the trailing edge of the slope. A Particle Image Velocimetry (PIV) and 32 cluster strain gauges were adopted to monitor the deformation of the tunnel structure and landslide soil, and the sliding surface, respectively. By means of a numerical simulation, the deformation characteristics of a tunnel crossing loess-bedrock strata are comprehensively described. The influence of a cyclic load on the mechanical behavior and displacement of the tunnel and sliding surface is discussed in detail. The experimental results show that the thrust required for the first landslide is the largest, during multiple loading and unloading. With the increase in loading and unloading time, the sliding thrust gradually decreases and eventually remains stable. The landslide presents a progressive failure mode. There is a stress concentration in the upper part of the tunnel, which causes the secondary sliding phenomenon. The deformation of the sliding surface mainly occurs in the upper soil of the tunnel. The deformation direction of the tunnel is consistent with the sliding direction, and the deformation of the sliding surface mainly occurs in the soil above the tunnel. When disturbed by an external force, the tunnel deforms downward, and, when unloaded, the tunnel has a small rebound deformation. However, with the increase in loading–unloading times, the rebound deformation of the tunnel gradually decreases, and the permanent deformation gradually accumulates until the tunnel fails. The research results can provide reference for the construction and protection of tunnel engineering in loess regions, and have reference value for the control of tunnels crossing landslides.

奥陶系灰岩具有成岩作用好、强度高、脆性大的特点.而岩体由于其特殊的形成条件,在岩体中存在大量的矿脉结构,易受风化作用的影响;同时,节理发育也会导致岩体劣化.以太行山奥陶系灰岩为研究对象,进行了室内干湿交替试验,得到了石灰石的劣化特征,建立了波速与空隙之间的数学模型.研究表明:(1)岩样声波波速在干湿交替过程中逐渐减小,并且横波比纵波的变化更为明显,由此说明灰岩的剪切特性发生较强的劣化;(2)试验中存在3种不同的劣化形式,即原生裂纹发育、矿脉延伸和表面剥蚀,在研究中以矿脉延伸为主要劣化形式;(3)矿脉劣化主要表现为颗粒脱落和空隙延伸,减弱了声信号能量的耗散;(4)利用大开空隙率、抗拉强度和点荷载强度建立了灰岩的劣化模型,可见其呈"S"型增长(减小).