以武汉市某工程的不规则深基坑为对象,运用ABAQUS有限元软件,建立无支护与有不同支护体系的基坑数值模型,研究支护体系的变形特性和空间效应分布规律,并将数值分析结果与实际监测数据进行比较以验证有限元模型的有效性,同时还对深基坑的整体稳定性进行了分析.结果表明:基坑大阳角部位产生最大变形,易失稳;阴角能有效抑制邻近区域土体位移的发展,有利于支护结构稳定;沿基坑长边方向,离角部越远,基坑土体位移量越大,至中部区域达到最大,空间效应也相应逐渐变弱,至中部基本消失;无内支撑时,支护桩桩顶水平位移最大,有内支撑时,接近桩身1/2处的水平位移最大;内支撑有减少桩身侧向位移的效果,对于桩身上半部分,内支撑能在一定程度上抑制基坑的空间效应;桩锚支护比双排桩支护更能有效提高基坑整体稳定性.

分别对湛江组结构性黏土中不同桩径、桩长及桩端闭口、开口形式的模型单桩进行不同休止时间段的原位静载试验,测定桩身应变及单桩承载力,通过对试验数据分析,得出如下结论:湛江组结构性黏土中,不同休止时间段的单桩在竖向荷载作用下的Q-s曲线均呈陡降型,极限状态明显;单桩具有明显时效性,单桩的时效性与时间成正相关,但在前15 d更加显著;在不同休止时间段,桩极限侧摩阻力均出现在桩基最下端,且随着深度的增加而增大;单桩的时效性与桩径、桩长有关,桩径越小,桩长越长,承载力时效性系数越大,承载力时效性越显著;桩端闭口形式的单桩承载力时效性比桩端开口形式的更显著.

According to the characteristics of storey-adding and reconstruction of buildings in the high intensity seismic region,this paper proposes a load balance method which lays emphasis on the uni-form distribution of load reduction and the balance between load reduction from the existing structure and load increment from the new storey.This method was applied to the storey-adding proj ect of a teaching building with frame structure whose seismic fortification intensity is eight.Three schemes to reduce load were made and then analyzed and compared by using PKPM and YJK softwares.The re-sults show that none of the original beams and columns needs to be reinforced when adopting the opti-mal scheme.So the proj ect cost is cut down and the construction period is shortened.

According to the characteristics of large excavation depth, complex surrounding environment, changes of groundwater level and difficulty in construction of a deep foundation excavation near the Yangtze River, according to the demand of engineering monitoring, a special family library is established on the basis of BIM model, the monitoring data of foundation excavation displacement, support internal force, deformation and groundwater level change are related to the model, the real-time monitoring and early warning function of BIM model are realized by 4D technology. The BIM model and the Web data system are combined to realize the remote monitoring and information management of the project, which plays an important role in the intelligent monitoring and information construction.

根据强度折减法,运用ABAQUS有限元分析软件探讨抗滑桩截面尺寸以及桩侧摩阻对边坡稳定性的影响.以特征部位的位移拐点作为边坡达到临界破坏状态的标准,并由求得的强度折减系数评价边坡的稳定性.结果表明:随着桩截面宽、高的增大,边坡的稳定性系数增大,但其增长速率越来越小;相对于桩截面尺寸,桩侧摩阻对边坡稳定性的影响很小,以至于可以忽略不计;当桩截面较小时,在保持桩截面面积不变的情况下,桩截面高大的抗滑桩在边坡中所起的作用越明显,但随着桩截面面积的增大,由桩的设置方位带来的边坡安全系数差异逐步减小;当桩间净距不变时,增加桩截面高比增加桩截面宽对边坡稳定性提高的作用更明显.因此,实际抗滑桩工程中控制和优化桩的有效截面尺寸,采用多桩减宽的方式将是经济有效的.

The response deformation method is commonly used for seismic analysis of underground structures. There are three aspects which can be improved for the problems and errors in calculation of the classic response de-formation method.One for foundation spring,one for the calculation of stratigraphic shear-force,and the another for both foundation spring and the calculation of stratigraphic shear-force.So the precision and efficiency of calculation of response deformation method are improved.

高层建筑结构中,中底部几层柱混凝土强度往往高于梁板混凝土的强度等级,为施工方便或施工技术不当,形成夹芯节点.当梁柱混凝土级差过大时,节点承载力不能满足要求.结合某一实际工程项目用Monte-Carlo法对钢筋混凝土夹芯节点抗剪承载力的可靠指标β进行计算,并对钢筋混凝土夹芯节点定量分析了荷载效应比、轴压比、结构重要性、节点混凝土强度、节点核心区箍筋间距和强度等因素对节点抗剪承载力的可靠指标β的影响.研究结果表明:在柱混凝土强度等级为C60情况下,强度差大于20MPa的夹芯节点,可靠度指标均小于3.7,节点核芯区的抗剪能力要求不能满足,应采取相应的措施予以加强.

A new transfer function considering softening of soil is obtained for Zhanjiang group structural clay.The load transfer method is adopted to explore the load transfer properties between the pile and soil in Zhanjiang group structural clay.the curve comprehensively describes the behavior of the clay from undamaged to damaged.Mathematical method is used to analyses the parameters in the function,and the analytical solution is obtained.The nonlinear fitting results of the observation data using this function are much closed to the testing results.Thereby,it proves that the proposed transfer function perfectly reflects the load transfer mechanism of the soil.

In light of the complicated geotechnical engineering and geological conditions in the middle and lower Yangtze River Area,an anti-floating optimal design was proposed for a certain underground civil air defense project,which used the discarded retaining piles in a deep foundation pit for anti-floating,removed the expanded head of the retaining piles,and reduced the thickness of concrete weightcoating for indoor anti-floating and the length of projected bottom.The results show that the optimal design has raised the anti-floating bearing capacity of civil air defense project under the street and solved the problem of anti-floating bearing capacity with the previous design.It has reduced the cost of foundation excavation,retaining project,and anti-floating project,and it has also reduced the risk and difficulty of foundation excavation and retaining(including rainfall).

Aimed at the anti-floating problems of underground project in JingZhou City,the issue presents a more economic and reliable scheme——the anti-floating scheme by the use of supporting structure.This paper elaborates the technological possibility of this scheme and introduces the methods of design and construction.By comparison between two different designs,the positive influence on construction costs is discussed in terms of the economical analysis.

To tackle the problems encountered in the renovation project of 500 kilovolt transmission tower foundation in the transmission lines from the hydro junction of Gezhouba Dam to Wuchang,the tower of ZB41 was taken as the prototype and an experimental model device was made in the laboratory to test the two foundation types: the big board foundation and the sheet pile(big-board-plus-micropile) foundation.The test results show that for the two schemes of foundations,the vertical bearing capacity of the foundation soil can satisfy the design requirements,and the horizontal bearing capacity can also meet the design requirements with the sheet pile foundation,but cannot with the big board foundation.The resistance horizontal load properties with the sheet pile foundation are three times more than those with the big board foundation.The scheme of the sheet pile foundation meets the design requirements of the renovation project.

运用有限元数值计算软件,PLAXIS,结合武汉某办公楼深基坑工程实例,模拟了基坑的分步施工过程,最终计算结果与现场监测值吻合良好,从而证明该计算方法可行。在此基础上,讨论并分析了桩-土接触界面强度折减因子和接触单元的虚拟厚度因子对支护结构水平位移、地表沉降以及基坑底部隆起的影响规律。研究表明:随着强度折减因子的增大,墙体变形会逐渐减小;而随着虚拟厚度因子的增大,墙体变形却逐渐增大。通过对比发现:强度折减因子和虚拟厚度因子对支护结构的位移的影响最大,对基坑底部隆起变形的影响最小;相对而言,强度折减因子比虚拟厚度因子对基坑位移的影响更明显。

Based on the earth pressure theory,an indoor model experiment was carried out to calculate and analyze the passive earth pressure acting on the retaining wall in the model of RTT movement with displacement taken into account.The analysis shows that the calculated values and the test values agree with each other well in the distribution of earth pressure along the wall height,the values of the total earth pressure,and the location of the action point of the total earth pressure.This suggests,it is feasible to use the calculation model to calculate the passive earth pressure in the model of RTT movement.Comparatively speaking,when n=0 the calculated values are more identical with the test values than when n=0.78,which may be relevant to the size effect of the box of the model test and the fact that the upper soil of the box of the model is disturbed more greatly.In addition,with the value of n increasing gradually,the soil is easier to reach Rankine's passive limit state.

Based on life cycle theory,the article establishes life cycle safety assessment model,and divides the deep foundation ditch project into four relative independent parts,prophase information prepare,general planning design,construction,and completion.Every part is one life cycle,and we can take every part into list analysis,which could get conclusion of safety index and economy index.Base on the four parts list analysis,we can take final bulk analysis,and evaluate the whole project system.

This paper presents a finite element method to simulate the process of staged excavation,and analyzes the factors that affect the horizontal displacement of retaining wall,such as the rigidity of supporting structure,prestressed value of the bolts,and the strength reduction of the contacted area between the soil and the supporting structure.The result shows that it is effective to control the displacement of wall by constructing the bolts in time,and that the increase in the rigidity of supporting structure and the prestressed value of the bolts can lead to the decrease of the horizontal displacement of retaining wall,yet it is not recommended to increase too much.The increase in the strength reduction can make the wall's horizontal displacement decrease gradually,and sometimes the influence is decisive.

Finite element application software,ANSYS,was employed to calculate and analyze the earth pressure of the sheet pile walls in deep excavation engineering.And the binomial expression was gained by utilizing the Matlab to fit the earth pressure along the depth of the sheet pile walls.Finally,the middle coefficient of earth pressure was gained by calculation.

The design of the rock bolts have been introduced in this paper.The results of the construction show the validity and superiority of using the rock bolt for Huatai billboard.

According to the fact that yield or failure of soil around anchor rods is the main failure form of the rods,based on elastic and plastic limit equilibrium theory,considering soil stability under the most unfavor- able conditions,it is proposed that the single anchor destruction form in the air slake terrain and soil layer is the tapered sharing failure that engendered by the soil around anchor.Supposing destruction form for single line of anchors is triangular prism and half taper composed destruction model,formula to calculate the bearing ca- pacity of ground anchors is developed.

本文应用混沌理论的基本原理,从系统控制的角度提出了针对施工管理的基本单元--工序管理的"接力技术"及其基本运行模式,该理论和方法对于改善和加强施工动态管理,实现系统优化具有积极的意义.

基于PKPM结构系列程序,提出制作多媒体CAI课件,根据多年教学经验和体会,提出CAI系统框图,探讨教学模块的设计.