岩土工程技术

Research on Acoustic Emission of Deep Buried Metamorphic Limestone under Uniaxial Loading Test

Li Zhipeng

2018, 32(1): 1-5. doi: 10.3969/j.issn.1007-2993.2018.01.001

[Abstract](34) [PDF 1357KB](7)

Abstract:
Deeply excavating the parameters of acoustic emission has great significance to research the characteristics of rock damage evolution,to understand the mechanism of rock fracture,and to predict the instability of rock mass and so on.Through the uniaxial compression with acoustic emission test,the damage and fracture mechanism of metamorphic limestone was studied deeply.The study shows that:The metamorphic limestone has significant hard and brittle characteristic,and during the test,the number of AE events,ringing count and energy showed a similar change trend of initial small-slow growthrapid growth-slow growth;the AE event space and time positioning results show that in the early stage of experimental loading,there were fewer AE events in the rock sample,and with the increase of load,the AE event first accumulated at the top of the rock sample and then gradually extended to the middle until it passed through the bottom of the sample,and the AE positioning results were consistent with the failure characteristics of rock sample.Through the AE monitoring technology,we can research the whole process of crack initiation,nucleation,expansion and interchange of the rock sample under loading,and it is of great significance to study the whole process of damage and failure of rock.

Horizontal Displacement Calculation and Monitoring Analysis of a Deep Foundation Pit in Qianhai Area

Qiao Liping

2018, 32(1): 6-9. doi: 10.3969/j.issn.1007-2993.2018.01.002

[Abstract](65) [PDF 1412KB](10)

Abstract:
The geological condition was poor in Qianhai area,Shenzhen,which was very unfavorable for the supporting project of foundation pit.In the background of a deep foundation pit of Qianhai area,the calculation of horizontal displacement were introduced in the paper,including difficulty analysis,unit calculation analysis and three-dimensional computation of exaction.The results were compared with the actual monitoring results,which was referenced as similar projects.

Analysis of Pile Foundation Bearing Capacity for High-rise Building and Beijing Tertiary Strata Engineering Geology Characteristics

Wang Yuan, Sun Hongwei

2018, 32(1): 10-16,20. doi: 10.3969/j.issn.1007-2993.2018.01.003

[Abstract](58) [PDF 2054KB](11)

Abstract:
In the western district of Beijing,Quaternary gravel sedimentary beneath widespread distribution of Tertiary strata,such this aquifer with nature vulnerable to environmental impact,which have characteristics of water softening obviously,poor disintegration durability and lower flooding saturated uniaxial compressive strength.M and G projects select the Tertiary strata as a pile tip bearing stratum;test data shows that the pile side resistance partly play,and pile tip resistance does not play,which due to the pile construction changes rock environment,and too thick sediment.At the same time,pile side resistance and pile tip resistance are not independent of each other,due to the hole bottom bearing stiffness support of there is a mutual impact mechanism.Based on the analysis of the characteristics of Tertiary strata and test pile data of the M and G projects,then Lize SOHO eventually choose thick layer of Quaternary gravel as pile bearing stratum;through analyzing Lize SOHO test pile data,which indicates that this region Quaternary gravel layer selected as pile bearing stratum could more effectively play pile side and pile tip resistance,then avoids pile construction disturbance to tertiary.The data of engineering pile test further validates that pile foundation pile design is reasonable.

An Integrated Management Platform of Multi-source Data for Geotechnical Engineering Based on MapGIS

Jin Xu, Guo Miwen, Zhang Yakun

2018, 32(1): 17-20. doi: 10.3969/j.issn.1007-2993.2018.01.004

[Abstract](55) [PDF 842KB](9)

Abstract:
GIS system has been widely used in the field of geotechnical engineering investigation and design for its powerful storage space,data management and analysis ability.According to the analysis result about engineering data of investigation,geotechnical and surveying,based on MapGIS 10 and SQL sever database,a new integrated management platform of multi-source data which built by internet and information technology is introduced in this paper.The engineering data can be showed intuitively on the map because of the powerful function of GISsystem.Data sharing and collaborative operation can be realized on the platform,and the functions such as browsing,analysis and query function,are provided.By using the platform,a large number of human and material resources and time are saved.In addition,the accuracy of survey data can be verified.This article may provide beneficial reference for information management and reusing of the engineering data in geotechnical engineering field through the primary exploration and research on GIS system's application in geotechnical engineering field.

Geological Risk and Technical Measures Research on Cretaceous Mudstone Strata during Subway Construction of Changchun District

Guo Hongmei

2018, 32(1): 21-27. doi: 10.3969/j.issn.1007-2993.2018.01.005

[Abstract](45) [PDF 1000KB](9)

Abstract:
The article makes a systematic research on basic geological features of Cretaceous mudstone by analysis of mineral composition,micro electric microscopy,physical and mechanical property test,expansion and slaking test of different weathering degree mudstone,wave velocity,resistivity test,anlysizing geological risk probably existing in subway construction in Cretaceous mudstone,putting forward corresponding technical measures and suggestions,providing a geological reference for subway design and construction.

Test Analysis for Uplift Coefficient of Post-grouting Bored Concrete Pile in Thick Sand Layers of Beijing Tongzhou District

Sun Yemo, Lu Pingzhen, Sun Hongwei

2018, 32(1): 28-33,49. doi: 10.3969/j.issn.1007-2993.2018.01.006

[Abstract](63) [PDF 2350KB](8)

Abstract:
This paper is based on the results of a field static load test on compression and uplift single piles in thick sand layers at Tongzhou district,Beijing.In this paper,each of three uplift and compression post-grouting of full length bored concrete piles from two test sites were selected.First,in order to obtain the shaft resistance curve of the each test pile,the field test data were processed.Second,compared the performance of shaft resistances between two types of piles under the ultimate load and then briefly analyzed the mechanical properties of uplift and compression piles in varies soil layers under increasing load.Third,the uplift coefficient of the soil layers was calculated by the ratio of the ultimate shaft resistance of the uplift and compression test piles.The range of the uplift coefficient of different soil layers and variation tendency varies in depth were discussed and analyzed in detail.It shows that the uplift coefficient ranges of the uplift piles in the two experimental sites are 0.34~0.67 and 0.31~0.63.The uplift coefficient range of soil layers above the middle of the test pile are 0.51~0.67 and 0.51~0.63.The uplift coefficient of soil layers near the lower-middle part of test piles are less than 0.5 in both test sites,due to insufficient performance of shaft resistance from surrounding soil layers.The results from this paper can provide the reference for design and theoretical research of uplift pile in thick sand layers of this area.

The Impacts for Oil Mine Geological Environmental Assessment from Loess Collapse and Surface Subsidence

Qian Kaizhu, Lv Jingjing, Guo Miwen

2018, 32(1): 34-36. doi: 10.3969/j.issn.1007-2993.2018.01.007

[Abstract](57) [PDF 521KB](5)

Abstract:
In recent years,the change of ground elevation has negative impacts on mining.Based on the investigations of geological environmental problems about ground elevation reduction,which include loess collapse in Northwest and surface subsidence in coastal region,the assessment has been done for impacts caused by them.Through comparative analysis,it describe in details about their causations,evolutions and impacts.For the significant impacts of problems,it proposes measures of restoration and monitoring which benefit for oil exploitation.

Countermeasure Study on Collapse Accumulation Body Landslide Treatment Adjacent Building

Mu Weigang, Liu Huancun, Wang Duli

2018, 32(1): 37-40,54. doi: 10.3969/j.issn.1007-2993.2018.01.008

[Abstract](77) [PDF 3151KB](13)

Abstract:
During the blasting excavation of mountain slope,due to improper blasting method,the shape of the slope is irregular and the slope is not reasonable.A large amount of rock mass remains on the slope.After the slope unloading,the deformation of the slope shoulder is large and the sustained collapse and destruction is occurred.It is a directly threat to the safety of construction activities of adjacent building on the slope bottom.According to the characteristics of this kind of slope and the geological structure,the causes and characteristics of the collapse accumulation body landslide was analyzed,and the non-limitation of workspace control method of collapse accumulation body landslide was put forward.It was proved by engineering practice that using the composite structure of back berm+slope protection pile+pillar-plate wall+bolt lattice girder to protect similar slope is safe and economical,and is convenient for construction.Support structure and slope bottom construction process can be parallel conducted,safety requirements and period of slope bottom construction is guaranteed,which provides a reference for similar slope management.

Analysis of Impact of Free Segment of Bolt to Prestress of Bolt in Pile-Anchor Support

Chen Quanfei, Zhao Jiewei, Gang Yuyin

2018, 32(1): 41-43. doi: 10.3969/j.issn.1007-2993.2018.01.009

[Abstract](43) [PDF 520KB](12)

Abstract:
Based on the deep foundation pit support project of a hospital in Beijing,this paper combined with measured data of prestressed bolt in pile-anchor support system,comprehensively analyzed the regular pattern with time by the different free segment of bolt.Under the same conditions,it is considered that the longer the free segment,the smaller the loss rate of the anchor prestress value.

Application Analysis of Exploration and Technological Means on Active Faults

Wang Tienan, Li Jun

2018, 32(1): 44-49. doi: 10.3969/j.issn.1007-2993.2018.01.010

[Abstract](45) [PDF 3628KB](45)

Abstract:
Active faults is very important to the influence of the engineering construction,especially the holocene active fault,can cause soil liquefaction,land subsidence,ground cracks and other secondary disasters.To reduce its influence on the construction site,how to detect active faults is the key of the engineering construction in unknown circumstances.The means and measures taken by is an important factor to find out the active faults of the accuracy of the assessment of active faults.This project area to take data collection,field investigation,integrated physical exploration and engineering geological prospecting and other means to carry on the comprehensive analysis to the position of the active faults,rock cover thickness and degree of rock weathering,provide reliable basis to find out the active faults.

Study on the Geological Hazards Features and Remediation Techniques of Swelling Rock Landslides, Guangxi, China

Wu Fu, Zhu Zhen, Xu Binlian

2018, 32(1): 50-54. doi: 10.3969/j.issn.1007-2993.2018.01.011

[Abstract](51) [PDF 745KB](11)

Abstract:
Remediation of landslides in swelling rocks is one of the extreme complexities in the field of geological engineering.The patterns of slope deformation and the consequent destructions are summarized based on the data of investigations and designs aiming at remediation for landslides in the typical swelling rocks,and the principle of the mechanical index determination in various application conditions are put forward as well,which would greatly facilitate the feasibilities in the remediation of landslides in swelling rocks.

2018 Vol. 32, No. 1