The Yining-Aksu Railway needs to cross the Tianshan Mountains twice from north to south. The natural climate and geological environment are harsh and complex at the crossing section of Nalati Mountain on the north side. The design and selection of the route scheme are obviously constrained by geological conditions, and the preliminary route selection survey requires to thoroughly determine all kinds of geological problems in the area. In this study, multisource data(e.g., Gaofen-2 images, Landsat 8 satellite images, and aerial high-resolution images) were used to perform detailed interpretation and analysis of the Nalati mountain crossing section, showing that there are densely developed landslide deformation areas along both banks of the Qiapu River, and the landslide groups on the left bank of the Qiapu River significantly impact the route scheme. The EW-NEE trending seismic-active fault zones in the area are mainly developed in the Meso-Cenozoic soft strata, with the southern margin of the Nalati fault and the Qiapu River fault as the typical ones, all of which have the phenomenon of local 're-movement'; the rockfall hazard regions in the upper reaches of the Gongnai River is mainly distributed in the intersection area of Highway G217 and G218 and its east areas, mainly in the sunny slope area.The results provide reliable basic data for field engineering geological surveys and route scheme comparisons, verifying the guiding function of the remote sensing in railway surveys in complex mountainous areas.
In order to protect the ancient buildings of the tunnel site and speed up the construction progress,the working face is increased by building the cross tunnel in the soft rock area.The construction of the intersection and cantilever beam is the important and difficult points of this kind of tunnel construction.Based on the Baitashan tunnel transverse tunnel project,combined with the risk control analysis in the construction process,the strengthening scheme is adopted for the intersection of the transverse tunnel and the main tunnel,and the main tunnel is constructed by using the strengthening CD method.The deformation analysis of the portal truss of the transverse tunnel is carried out.The maximum deformation at the top is 7.lcm,which is less than the reserved deformation of the main tunnel of 120mm and meets the design requirements.At the same time,the internal force and deformation of the actual truss structure will be less than the calculated value due to the anchoring effect of the locking anchor pipe on the top and side walls of the portal truss,which can be used as a safety reserve for theoretical calculation.The good field application provides a reference experience for this kind of engineering.
The geological strength index(GSI)for the conventional Hoek-Brown model is normally determined by field work,which is greatly affected by the experience of the engineers.Based on the relationship between wave velocity,GSI index and modulus,a quantitative method to calculate GSI index in the Hoek-Brown model is presented by using the wave velocity.The generalized GSI index with respect to the construction disturbance is also proposed in this paper.By the comparison with the normal methods,the proposed method shows the good performance.The prediction of the bearing capacity of slate rock in the Changsha project verifies the proposed method.The proposed method is meaningful for using Hoek-Brown model in engineering practice.
The production of fundamental geographic entities and the construction of fundamental geographic entity databases are the core tasks of the current new fundamental surveying and mapping and real scene 3D China construction.This paper focuses on the production of fundamental geographic entity data and takes the EPSE platform as an example,combined with the production practice in Guangzhou,this paper introduces in detail the production of fundamental geographic entity data in two-dimensional form based on existing data conversion and geographic scene data generation,as well as the production of fundamental geographic entity data in three-dimensional form such as label,cutting and reconstruction monomer.The relationship and difference between stock data conversion mode and integrated incremental data production mode are analyzed,which can provide reference for other cities to carry out fundamental geographic entity data production.
With the vigorous development of tunnel engineering technology in our country,it is possible that tunneling project through the densely built areas or important cultural relics protection areas.For tunnel builders,how to ensure the safety of upper structures in complex environments is always an important issue.The existing control standards mainly focus on the influence of foundation deformation on the durability of superstructure.However,there are few researches on the control standards of structural deformation from the perspective of the materials and internal forces of the structure itself.This study is based on a tunnel project which crossing the soil city wall in Shanxi,the relationship between the stratum deformation and the structural internal force is established,which combines with the characteristics of city wall materials,elastic-plastic theory and Peck settlement trough principle,and the settlement control standard that can truly reflect the stress of crossing buildings is derived.It is verified by using numerical simulation and field measurement analysis,which provides the reference and a fresh idea for similar projects in the future.
