岩土工程技术

XRD(X-ray Diffraction) Analysis of Deep Mixing Pile Foundation Treatment

Li Dongwei

2018, 32(5): 217-221,260. doi: 10.3969/j.issn.1007-2993.2018.05.001

[Abstract](42) [PDF 1296KB](5)

Abstract:
This study combined with the cement-soil mixing method,the X-ray diffraction(XRD) analysis of the undisturbed soil and the treated cement-soil microstructure in a shipbuilding reclamation site is performed to describe and analyze different conditions from a microscopic perspective.Including undisturbed soil,soil,depth,types of solidified materials,etc.Cement-soil mixing method is used to reinforce the deep foundation of the site,and the suggestions improving the strength of the cement-soil mixing pile are specifically proposed to guide the optimization and improvement of the actual project.

Accident Analysis and Reinforce Treatment for Drill Grouting Piles Foundation of Marine Mucky Soil Area

Shu Zhaoran, Cao Ruina, Liu Zhongchang

2018, 32(5): 222-225. doi: 10.3969/j.issn.1007-2993.2018.05.002

[Abstract](32) [PDF 543KB](9)

Abstract:
This article analyses the pile foundation which is not qualified for the integrity and bearing capacity by the drill grouting piles test in the marine mucky soil area.The main reason has been found out that the drill grouting piles in marine mucky soil area will lead to concrete excursion and erosion.Meantime,this article also studied how to utilize the current pile foundation bearing capacity via acceptance test,additional test and design load audit,further strengthen the pile foundation and save invest cost.

Application of Different Central Frequency Antennas of Ground Penetrating Radar in the Detection of Ancient Wall Diseases

Luo Huiguo, Zhang Qingli

2018, 32(5): 226-230,265. doi: 10.3969/j.issn.1007-2993.2018.05.003

[Abstract](48) [PDF 2741KB](7)

Abstract:
It is high detection precision,convenient and flexible,high efficiency of ground penetrating radar;and according to the type of diseases,the depth of the burial and the detection precision,the different types of antenna combination can be selected to achieve the best detection effect.The method does not cause any damage to the detection target in the detection process,and the result is intuitive.It is the most suitable method to detect the diseases of the ancient wall at present.In this paper,100 MHz,270 MHz,400 MHz,900 MHz and 1600 MHz antennas are used to test the top and side surfaces of the ancient wall,and the locations,scopes,depths and scales of the diseaes are explored in an all-round way.According to the ground penetrating radar atlas of different central frequency antennas,the effectiveness,advantages and disadvantages,and application scope of different frequency antennas are compared and analyzed in detecting the ancient wall diseases.

Application of Geotechnical Investigation Techniques in Construction of Prestressed Pipe Pile in Collapsible Loess Area in North China

Dang Zhirong, Zhang Xiaobo, Su Libao

2018, 32(5): 231-236,271. doi: 10.3969/j.issn.1007-2993.2018.05.004

[Abstract](47) [PDF 926KB](8)

Abstract:
Effect in the construction of large area prestressed pipe pile can make near completed pile or building produce displacement,this phenomenon is common in soft soil area in the south,but the collapsible loess area is very rare in the north.This article through to the collapsible loess region,the analysis of the survey report of a certain power plant in Shanxi Province,find out the prestressed pipe pile construction in adjacent has been built based on boiler room of pile foundation construction completion and the cause of the displacement of pile caps,put forward a variety of solutions,and recommend using slope unloading,adjusting the construction sequence and comprehensive treatment methods to slow down the speed of construction,effectively solve the problem,to prevent the project quality accident.This method is of great significance to the engineering of geotechnical engineering in solving the technical problems in geotechnical construction.

Discussion on Emergency Investigation of Geological Disasters in Beijing

Huang Laiyuan

2018, 32(5): 237-241. doi: 10.3969/j.issn.1007-2993.2018.05.005

[Abstract](71) [PDF 624KB](7)

Abstract:
The emergency investigation is an important part of the emergency management system of geological disasters,and it is the technical basis for the emergency decision of the superior departments.The sudden geological disasters in Beijing have the characteristics of many points,wide range,small scale and large negative impact;the emergency investigation procedures,techniques and requirements of geological disasters have their own regional characteristics.Based on the summary and analysis of the previous geological disasters emergency investigation in Beijing,this paper discusses the history and present situation of emergency investigation work.Through the discussion of the current investigation system,some suggestions are put forward.

Analysis on Deformation Mechanism and Stability of Zhengjiaping Deformation Slope

Cao Ting, Wang Lijun, He Xin

2018, 32(5): 242-246. doi: 10.3969/j.issn.1007-2993.2018.05.006

[Abstract](46) [PDF 2555KB](8)

Abstract:
This paper takes Zhengjiaping deformation as engineering example,through field geological survey,exploration tunnel and drilling exploration and other means,deformation evolution process,deformation destruction characteristics and genetic mechanism are research and analysis of the deformation slope.According to deformation characteristics,the deformation slope is divided intoⅠ,Ⅱ,Ⅲarea.According to the intensity of toppling deformation in the rock,it can be divided into three types:“broken loose deformation zone”,“strong dumping deformation zone”and“weak dumping deformation zone”.The deformation mechanism of the deformation slope is determined as“the toppling deformation is strong,engineering excavation and reconstruction+water storage transformation+rainfall infiltration,the aggravation of deformation”.Based on the deformation destruction characteristics and genetic mechanism of the deformation slope,a suitable deformation failure mode is proposed.Morgenstern-Price method is used to analyze the stability of the deformation slope in the SLIDE software.

Influence Evaluation of Existing Road and Metro Tunnel Deformation during Shield Tunnel Construction

Luo Kang, Xu Jing, Zheng Yuhui

2018, 32(5): 247-250. doi: 10.3969/j.issn.1007-2993.2018.05.007

[Abstract](52) [PDF 1114KB](12)

Abstract:
This paper relies on the shield construction of the crossing tunnel in Sichuan university West campus in Chengdu.Through monitoring the deformation of road above the crossing tunnel and metro tunnel below;and combining with the finite element numerical simulation to simulate the shield tunnel construction process of crossing tunnel by 3D-FEM;combined with field measurement results comparative analysis and impact assessment are carried out.

Study on Calculation Method of Empirical Coefficient of Water Outflow in Deep Foundation Pit of Suspended Waterproof Curtain

Wang Shiqi, Sun Huabo, Zhao Gang

2018, 32(5): 251-254. doi: 10.3969/j.issn.1007-2993.2018.05.008

[Abstract](54) [PDF 567KB](7)

Abstract:
With the development of the entities and concepts such as urban underground complex,rail transit and sponge city,the building space extends deeper to the underground,groundwater control becomes more and more prominent in the construction,and its influence on environment and groundwater safety is more and more important,especially for the multilayer groundwater research and control scheme.It is the development direction of the deep foundation pit design that curtain of water cut is selected with a small amount of dewatering method.Based on the analysis of the actual cases,the upper ground water is obstructed by the curtain to the bottom,the suspended curtain is used to control the underground water,and the empirical coefficients of the water outflow is studied and counted in the foundation pit of the suspended curtain.

Influence of Deep Foundation Pit Excavation on Stability of Nearby Metro Tunnel in Kunming Soft Soil Area

Guo Yanhui, Wang Jianguo, Gao Caikun

2018, 32(5): 255-260. doi: 10.3969/j.issn.1007-2993.2018.05.009

[Abstract](47) [PDF 3354KB](6)

Abstract:
A deep foundation pit engineering of construction project in Kunming soft soil area may affect the stability of metro tunnel of the Line 3.On the basis of field exploration results and data analysis,using three-dimensional finite difference method,analyzing the distribution law of displacement,stress,plastic damage zone of the metro tunnel in the process of excavation unloading of the deep foundation pit.Results show that the influence of the deep foundation pit excavation on the subway tunnel is very small under the design excavation support scheme of the deep foundation pit,which conforms to the technical standards of corresponding metro structure protection,can ensure the safety use of metro tunnel.Research results provide certain reference for the engineering stability and security prevention.

Application of Accuracy Location Technique for Intermediate Upright Prop in the Strut

Ji Xiaopeng, Shao Yuanqing, Che Dong

2018, 32(5): 261-265. doi: 10.3969/j.issn.1007-2993.2018.05.010

[Abstract](36) [PDF 2196KB](7)

Abstract:
The positioning and perpendicularity control of the intermediate upright prop have always been important and difficult points in the construction,as which is one of the key components in the internal strutted retaining structure system;and is also the key structure of the vertical braced structure system.It is the key technology of the upright prop construction how the accuracy location of the upright prop is carried out.Combined with a project in Beijing,the technique of the orifice locator device,the lattice columns union,the connection between steel-lattice and steel reinforcement cage is applied to achieve the accuracy location of the intermediate upright prop.The practice shows that the technique is low in cost and convenient in construction,and can meet the accuracy of positioning of the intermediate upright prop.

Optimization of Design Parameters for Double Row Piles Retaining Structure

Guo Lin, Li Zhongxiang, Cai Fei

2018, 32(5): 266-271. doi: 10.3969/j.issn.1007-2993.2018.05.011

[Abstract](42) [PDF 1999KB](15)

Abstract:
The double row pile support structure has the characteristics of short construction period,small construction area and large supporting depth,so it is widely used.Because the stress is relatively complex of structural system,design and calculation theory is not very mature,some problems have been found in engineering practice,so it is necessary to conduct the thorough research to the design parameters of double row piles and to explore effective improvement method.In this paper,the finite difference software FLAC 3Dis used to set up the numerical analysis model to study its force and deformation distribution law,and then proposed the optimization and improvement measures for the support structure.

2018 Vol. 32, No. 5