Yanjun Shang

A super-large landslide in Tibet in 2000: background, occurrence, disaster, and origin

On April 9, 2000, a super-large landslide (3 x 10(8) m(3)) occurred along Zhamu Creek, southeast Tibet. As a result, a landslide dam formed and the Yigong River was blocked. A channelized diversion was constructed for prevention of overtopping. Two months later on June 10, a catastrophic flood resulting from the failure of the landslide dam caused a serious loss of property. This is the second of landslide occasion dam formation and flooding occurrence at the same site since 1900.

A case history of Tunnel Boring Machine jamming in an inter-layer shear zone at the Yellow River Diversion Project in China

This is a case study of a Tunnel Boring Machine (TBM) jamming in a section of the Connection Works No. 7 tunnel of the Yellow River Diversion Project (YRDP) in China. Analysis of tunnel lithology, rock convergence by shearing, rock strength and ground stress, indicates that a high rate of convergence within an inter-layer shear zone in the lower part of an anticline was a dominant factor in the jamming. In addition, the shield encountered unfavorable tunnelling conditions in the form of wet clay, groundwater inflow, and cavities, coincident with tensile stresses in the lower part of an adjacent syncline. Based on these diagnoses, economical and quick measures were adopted, including additional excavation outside of the shield leaving free space to release the TBM. After 9 days of being jammed, the TBM was totally released and resumed normal excavation. This example highlights lessons learned from folding and inter-layer shear zone in TBM tunnelling.

Retrospective case example using a comprehensive suitability index (CSI) for siting the Shisan-Ling power station, China

Abstract The purpose of this paper is to present a retrospective case example of using the rock engineering systems (RES) methodology to site a pumped storage power station in China. With such a siting problem, there are many interacting factors governing both the site and the specific underground position of the powerhouse. The RES approach, based on an interaction matrix for semi-quantitative characterization of the factors and their interactions, is used to develop a comprehensive suitability index (CSI). In this way, the factors governing the geological and rock mechanics related factors are structured and evaluated. Additionally, the complexity of the decision making process is condensed to the CSI values for different potential sites and underground locations, a higher CSI value indicating a more suitable site. The retrospective analysis uses information from the investigations made during the actual site investigation and design work for the Shisan-Ling Power Station, China — which has been constructed. For the first stage, site selection for the overall engineering arrangement, 11 parameters concerned with geology, geomorphology, engineering layout, environment, cost and construction are taken into account. After comparison of site options in conglomerate, andesite and limestone formations, the conglomerate formation proved to be most favorable — because it has the highest CSI value. For the second stage, specifically locating the underground powerhouse, another seven parameters associated with faults, joints, groundwater, etc. are evaluated. As a result, position II proved to be the most favorable location for the powerhouse. Since these were the same conclusions reached during the actual investigations, this retrospective application of the CSI demonstrates the value of the RES methodology and associated indices for assisting in rock engineering design.

Intelligent back analysis of displacements using precedent type analysis for tunneling

Abstract Based on comprehensive monitored data obtained from typical tunnel projects, and by using engineering experiences of experts together with numerical modeling results, the precedent type analysis (PTA) technique developed was for back-analyzing in situ stress and elastic modulus of rock masses surrounding tunnels. Then, the PTA is used as a supporting technique in the method of intelligent back analysis (IBA). The IBA method can integrate the mechanism analysis with experimental identification. Such integration is based on ‘certainty factors’, and is implemented with the computer program BMP90 with a global inference engine. The program BMP90 can solve a series of back analysis problems—such as identifying potential problems to be encountered during back analysis, assessing the strategy to be adopted, selecting criteria for back analysis, and ensuring convergence of back analysis results. Based on the engineering applications to approximately 100 tunnel projects in China, it is found that the IBA method supported by the PTA technique can be successfully applied to tunnel projects, i.e. back-analyzing the lateral in situ stress factor (λ), and the elastic modulus ( E ) of rock masses. The method of IBA supported by PTA and its application to a tunnel project are presented in this paper.

Engineering geological zonation using interaction matrix of geological factors: An example from one section of Sichuan-Tibet Highway

In linear engineering projects such as those of the highways and railways in the northern Yarlu-Tsangpu Grand Canyon of Tibet that cross various geological and geomorphological units, engineering geological zonation must be carried out in advance because of complicated and diverse engineering geological conditions. Previous zonations have been based on qualitative approaches together with an overview of regional physio-geographic and geological settings. Such an approach is suitable for a broad regional development plan. However, it is not adequate for remediation of highways. In this paper, an interaction matrix approach was adopted and applied as an Engineering Geological Zonation Index (EZI) for the semi-quantitative analysis of the data from the Basu—Linzhi section of the Sichuan-Tibet Highway in China. Eight zonations and 19 sub-zonations of the section were made and evaluated, in accordance with a qualitative evaluation procedure. The results of the research presented in this paper will provide useful information for future railway design and construction.

The Cultural Relics Distribution Characteristics Along the Canal Line and Appraisal of its Influence by the Middle Route Project for Water Transferring from South to North China

Assessments of the impacts of environmental hazards on ecological systems and human health have become a subject of ever-increasing importance. In this work, we extend current ecological hazard evaluation to the problem of protecting cultural relics from hazards attributable to the presence of a large-scale canal system being planned in China. The development and utilization of water resources must be closely combined with the preservation of cultural relics. The Middle Route Project for Water Transfer from South to North China (MRWT) is a current example. In this paper, the engineering background of this project is briefly introduced. The distribution of cultural relics related to it is also summarized in terms of different geographical divisions. An influence index E = f(L, δh, k, I, v, s) is introduced to measure the comprehensive effect of the canal on cultural relics. Because this function is really established at the preconstruction stage, it is treated by use of fuzzy mathematics. Each cultural relic has its own E value. Cultural relics with E values greater than 0.75 should be paid high attention, while those with E less than 0.5 may generally be ignored. What must be preserved through use of engineering measures are cultural relics with E values greater than 0.9. As to those cultural relics with E ranging between 0.5 and 0.75, whether they should be preserved with engineering controls depends upon practical circumstances specific to each relic.

Geophysical Investigation of Fresh-Saline Water Interface: A Case Study from South Punjab, Pakistan

The importance of the study of fresh-saline water incursion cannot be over-emphasized. Borehole techniques have been widely used, but they are quite expensive, intrusive, and time consuming. The electrical resistivity method has proved very successful in groundwater assessment. This advanced technique uses the calculation of Dar-Zarrouk (D-Z) parameters, namely longitudinal unit conductance, transverse unit resistance, and longitudinal resistivity has been employed by using 50 vertical electrical sounding points to assess the groundwater and delineate the fresh-saline water interface over 1045 km2 area of Khanewal in Southern Punjab of Pakistan. The x-y plots and maps of D-Z parameters were produced to establish a decipherable vision for the occurrence and distribution of different water-bearing formations of fresh-saline water aquifers through a complicated situation of intermixing of different resistivity ranges for fresh-saline water bodies. This technique is useful to reduce the ambiguity produced by the process of equivalence and suppression which cause intermixing in differentiating fresh, brackish, and saline aquifers during interpretation. The fresh-saline water interface is correlated very well with the previous studies of water quality analysis carried out in Khanewal area. The results suggest that the D-Z parameters are useful for demarcating different aquifer zones. The behavior and pattern of D-Z parameters with respect to occurrence and distribution of different water-bearing formations were effectively identified and delineated in the study area.

Modifications to the GSI for granite in drilling

The Geological Strength Index (GSI) is widely used to estimate mechanical parameters of rock mass, but estimation of GSI is relatively subjective because of the lack of quantitative parameters. Hence, the existing method for estimating GSI is not suitable for rock samples from drilled cores. Inspired by the GSI estimation method of flysch (Marinos and Hoke, Proceedings of the GeoEng2000 at the international conference on geotechnical and geological engineering, Melbourne, Technomic publishers, Lancaster, pp 1422–1446, 2000), this paper proposes two parameters, the rock mineral condition and rock core length, for use in a modified, more quantitative method for estimating GSI. This modified method can be used for granite specimens from drilled cores. It uses images of typical core samples instead of the sketches given by Hoek’s GSI estimation method. A modified chart of GSI for granite, which is suitable for estimating mechanical parameters of rock mass from drilled core samples, is then developed. The E (elastic modulus) and Qult (ultimate bearing capacity) values obtained using our modified method were compared with those from experimental data; the results indicate that the modified method can produce reasonable GSI values and can be used to estimate the mechanical parameters of rock mass from drilled cores.

Geophysical Assessment of Groundwater Potential: A Case Study from Mian Channu Area, Pakistan: M. Hasan et al. Groundwater xx, no. x: xx-xx

An integrated study using geophysical method in combination with pumping tests and geochemical method was carried out to delineate groundwater potential zones in Mian Channu area of Pakistan. Vertical electrical soundings (VES) using Schlumberger configuration with maximum current electrode spacing (AB/2 = 200 m) were conducted at 50 stations and 10 pumping tests at borehole sites were performed in close proximity to 10 of the VES stations. The aim of this study is to establish a correlation between the hydraulic parameters obtained from geophysical method and pumping tests so that the aquifer potential can be estimated from the geoelectrical surface measurements where no pumping tests exist. The aquifer parameters, namely, transmissivity and hydraulic conductivity were estimated from Dar Zarrouyk parameters by interpreting the layer parameters such as true resistivities and thicknesses. Geoelectrical succession of five-layer strata (i.e., topsoil, clay, clay sand, sand, and sand gravel) with sand as a dominant lithology was found in the study area. Physicochemical parameters interpreted by World Health Organization and Food and Agriculture Organization were well correlated with the aquifer parameters obtained by geoelectrical method and pumping tests. The aquifer potential zones identified by modeled resistivity, Dar Zarrouk parameters, pumped aquifer parameters, and physicochemical parameters reveal that sand and gravel sand with high values of transmissivity and hydraulic conductivity are highly promising water bearing layers in northwest of the study area. Strong correlation between estimated and pumped aquifer parameters suggest that, in case of sparse well data, geophysical technique is useful to estimate the hydraulic potential of the aquifer with varying lithology.

Modification of rock mass strength assessment methods and their application in geotechnical engineering

Due to complicated structures and discontinuities in surrounding rock mass, existing empirical failure criteria cannot meet the requirements of engineering practice such as tunnels. To improve estimation accuracy on the strength of rock mass with joints, a modified chart of the Geological Strength Index using Hoek–Brown criteria was further tested to estimate rock mass strength [Lin et al. (2014) Bull Eng Geol Environ 4(73):1245–1258], and, in this paper, new strength estimation equations for jointed rock mass were then modified based on a large dataset obtained from Chinese projects. Here, standard drilling time is first introduced and described in this study, and then used as a parameter to estimate rock strength. Different empirical formulas based on joint density, rock mass classification, Hoek–Brown criteria, and elastic wave velocity are thus used to estimate rock mass strength by using data from the Jiubao tunnel. The results estimated based on different empirical formulas were similar, indicating that the modified assessment method presented in this paper can be used to estimate rock mass strength under certain circumstances. Cross-correlation of different empirical methods provides significant confidence in predicted rock mass strength calculations.