Yiguo Xue

An Attribute Synthetic Evaluation System for Risk Assessment of Floor Water Inrush in Coal Mines

An attribute synthetic evaluation system was combined with attribute mathematical theory and the analytic hierarchy process (AHP) to evaluate the risk of floor water inrush in coal mines. The evaluation indices of floor water inrush were divided into continuous variable indices, which were quantitatively graded according to floor water inrush risk and discrete variable indices, which were qualitatively graded by expert opinion. Single index attribute measurement functions were constructed to calculate the membership degree of the continuous variable indices. The membership degree of the discrete variable indices were evaluated using expert opinion eliciting techniques, such as the Delphi method. The contribution weighting of the evaluation indices were rationally distributed by the AHP. A confidence criterion was applied to discern the risk of floor water inrush. These results were compared with those from a secondary fuzzy comprehensive evaluation; the results from the present method agrees well with field-observed results. This approach provides a referential methodology for engineers to systematically assess and manage risk of floor water inrush in coal mines.ZusammenfassungEin attributsynthetisches Bewertungssystem wurde mit attributmathematischer Theorie und dem analytischen Hierarchieprozess kombiniert, um das Risiko von Liegendwassereinbrüchen im Kohlenbergbau zu bemessen. Kennziffern für Liegendwassereinbrüche wurden in kontinuierliche Variable, welche quantitativ nach dem Liegendwassereinbruchsrisiko klassiert wurden, und in diskrete Variable unterteilt. Die Letztgenannten wurden nach Expertenbefragung gestaffelt. Funktionen einzelner Indexattributmessungen wurden erstellt, um den Grad der Gruppenzugehörigkeit der Kennziffern kontinuierlicher Variabler zu berechnen. Der Grad der Gruppenzugehörigkeit der Kennziffern diskreter Variabler wurde mittels Techniken der Expertenbefragung evaluiert, wie etwa der Delphimethode. Die Gewichtung des Anteils der Bemessungskennziffern wurde mit dem analytischen Hierarchieprozess rational verteilt. Ein Konfidenzkriterium wurde angewandt, um das Risiko eines Liegendwassereinbruches zu erkennen. Die Ergebnisse wurden mit jenen verglichen, welche mittels sekundärer ganzheitlicher Fuzzy-Bewertung erstellt wurden; die Ergebnisse der vorgestellten Methode stimmt mit Feldbeobachtungen überein. Dieses Vorgehen stellt Ingenieuren eine Referenzmethode zur Verfügung, um das Risiko von Liegendwassereinbrüchen im Kohlenbergbau systematisch einzuschätzen und handzuhaben.ResumenUn sistema de evaluación sintética de atributos se combinó con la teoría matemáticas de atributos y el proceso analítico jerárquico (AHP) para evaluar el riesgo de irrupción de agua desde el piso en minas de carbón. Los índices de evaluación de irrupción de agua fueron divididos en índices variables continuos que fueron graduados cuantitativamente de acuerdo al riesgo de irrupción de agua desde el piso e índices variables discretos, que fueron graduados cualitativamente por opinión experta. Se construyeron funciones de medición de índices de atributos para calcular el grado de pertenencia de los índices variables continuos. El grado de pertenencia de los índices de variable discreta fue evaluado usando técnicas de opinión experta como por ejemplo, el método Delfos. El peso de la contribución de los índices de evaluación, fue racionalmente distribuido por el AHP. Un criterio de confidencia fue aplicado para discernir el riesgo de irrupción de agua. Estos resultados fueron comparados con aquellos obtenidos con una evaluación integral difusa; los resultados del método presentado aquí coinciden bien con los resultados observados en el campo. Esta aproximación proporciona una metodología referencial para ingenieros para relevar y manejar sistemáticamente el riesgo de irrupción de agua desde el suelo en minas de carbón.摘要基于属性数学理论和层次分析方法,提出了一种用于评价煤矿底板突水风险的属性综合评价系统。首先,将底板突水评价指标划分为连续型和离散型两类,连续型变量指标根据底板突水风险进行定量分级,离散型变量指标依据专家意见进行定性分级。其次,通过构建单指标属性测度函数,计算得到连续型变量指标的隶属度,并采用德尔菲法获得离散型变量指标的隶属度。然后,采用层次分析法构造判断矩阵来确定评价指标的权重,应用置信度准则确定底板突水的风险等级。最后,将本方法与二次模糊综合评价法的评价结果作对比分析,本方法评价结果与现场结果具有较好的一致性,为煤矿底板突水风险评估与管理提供了一种有效指导方法。

Predicting geological hazards during tunnel construction

Abstract The complicated geological conditions and geological hazards are challenging problems during tunnel construction, which will cause great losses of life and property. Therefore, reliable prediction of geological defective features, such as faults, karst caves and groundwater, has important practical significances and theoretical values. In this paper, we presented the criteria for detecting typical geological anomalies using the tunnel seismic prediction (TSP) method. The ground penetrating radar (GPR) signal response to water-bearing structures was used for theoretical derivations. And the 3D tomography of the transient electromagnetic method (TEM) was used to develop an equivalent conductance method. Based on the improvement of a single prediction technique, we developed a technical system for reliable prediction of geological defective features by analyzing the advantages and disadvantages of all prediction methods. The procedure of the application of this system was introduced in detail. For prediction, the selection of prediction methods is an important and challenging work. The analytic hierarchy process (AHP) was developed for prediction optimization. We applied the newly developed prediction system to several important projects in China, including Hurongxi highway, Jinping II hydropower station, and Kiaochow Bay subsea tunnel. The case studies show that the geological defective features can be successfully detected with good precision and efficiency, and the prediction system is proved to be an effective means to minimize the risks of geological hazards during tunnel construction.

Multi-component and multi-array TEM detection in karst tunnels

Emerging applications of transient electromagnetic methods (TEM) in tunnelling require higher resolution on the distributions and shapes of low resistivity bodies, such as karst water and karst pipes, using multi-component and multi-array receivers. However, there are no apparent resistivity definitions for both vertical and horizontal components with offsets inside the loop. Although the raw field can show the differences of the earth electric structure, it is not straightforward. Apparent resistivity is very convenient and easy for engineers. We have developed a method for multi-component and multi-array TEM which can be applied in tunnelling and defined the expressions of apparent resistivity. This method takes advantage of the difference in resolution among components. A homogeneous half-space model and four typical three-layered models are used to test the effectiveness of the new definition. A field case history is carried out and analysed to demonstrate the viability of this technique. The results suggest that it is feasible to use the technique in tunnelling, especially for identifying the spatial distribution of karst water and karst pipes.

Study on Major Construction Disasters and Controlling Technology at the Qingdao Kiaochow Bay Subsea Tunnel

ABSTRACT Li, S.; Tian, H.; Xue, Y.; Su, M.; Qiu, D.; Li, L., and Li, Z., 2015. Study on major construction disasters and controlling technology at the Qingdao Kiaochow Bay Subsea Tunnel. The Qingdao Kiaochow Bay Subsea Tunnel was difficult because of complex geological conditions, including the 18 faults crossing the tunnel, large construction section, and high risks for collapse and water inrush. These conditions were considered as a background of this study. Geological disasters, such as collapse and water inrush, were introduced as the two main geological disasters during construction. Moreover, the advanced support pretreatment measures that aimed to address faults during construction and effectively prevented collapse disasters were introduced. For the water inrush disaster, geological forecasting was used to predict underground water location, and advanced grouting was adopted. The presented disaster control technologies were proven effective in the construction of the Qingdao Kiaochow Bay Subsea Tunnel. This study provides a certain reference value for disaster control technologies for subsea tunnel construction.

Practice of TEM tunnel prediction in Tsingtao subsea tunnel

Summary Introduce the TEM tunnel prediction and its application in Tsingtao subsea tunnel. Give an introduction about the apparent longitudinal quadratic differential conductance imaging method. It has the characteristic of more sensitivity to geological surfaces. Finally, give a field test case of TEM prediction in Tsingtao subsea tunnel. The result forecast two water bearing structure ahead of the tunnel face successfully.

Deformation features and failure mechanism of steep rock slope under the mining activities and rainfall

Underground mining activities and rainfall have potential important influence on the initiation and reactivation of the slope deformations, especially on the steep rock slope. In this paper, using the discrete element method (UDEC), numerical simulation was carried out to investigate deformation features and the failure mechanism of the steep rock slope under mining activities and rainfall. A steep rock slope numerical model was created based on a case study at the Wulong area in Chongqing city, China. Mechanical parameters of the rock mass have been determined by situ measurements and laboratory measurements. A preliminary site monitoring system has been realized, aiming at getting structure movements and stresses of unstable rock masses at the most significant discontinuities. According to the numerical model calibrated based on the monitoring data, four types of operation conditions are designed to reveal the effect of mining excavation and extreme rainfall on the deformation of the steep rock slope.

Longitudinal jet ventilation calculation and application of long highway tunnel

When a vehicle passes through a long highway tunnel, the smoke it discharges accumulates in the tunnel. High smoke concentration has an important influence on the driver’s health and driving safety. The use of numerous jet fans to diffuse the smoke causes excessive energy consumption, so it is of significant practical value to design suitable tunnel ventilation.,The study is based on the continuum hypothesis, incompressible hypothesis, steady flow hypothesis and similar hypothesis of gas in a long highway tunnel. These hypotheses calculate the gas emissions and wind demand in a long highway tunnel given the deployment of the jet fan program.,This program selects each of the two 1120-type jet machine group and sets up 13 groups; each group has an interval of 184.5 m in the end. The analysis of air test results when the tunnel is in operation shows that CO and smoke concentrations meet the design requirements, which can provide reference for a similar engineering design later.,At present, a highway tunnel is recognized at home and abroad by means of clearance of longitudinal ventilation, which is 2,000 m. In view of this, this paper is based on the theory of longitudinal jet ventilation of a highway tunnel, whose length is more than 2,000 m, to calculate the ventilation and apply it to a tunnel’s ventilation design.

Risk assessment of water inrush in karst tunnels excavation based on normal cloud model

Water inrush in karst tunnels is a dynamic process in which internal and external factors are involved. The evaluation of this process is fuzzy, complex, and uncertain. In the current research, few articles give full consideration to the fuzziness and randomness of the water inrush evaluation with useful dynamic feedback. A new assessment method has been proposed for the water inrush evaluation based on a combination of the weighting method and normal cloud model. Specifically, an evaluation index system is forged and each index is quantitatively classified into four grades. A synthetic weighted algorithm combining the analytic hierarchy process, entropy method, and statistical methods is proposed to assign the index weight rationally. Based on the cloud generator algorithm, three numerical characteristics are calculated and a sufficient number of cloud droplets are generated. The membership degree of each index belonging to each grade is constructed and the integrated certain grades are determined. In this paper, the multi-factor normal cloud assessment method is applied to the risk assessment of the Qiyueshan tunnel. The assessment result of the risk grade is accurate, that is, the water inrush risk of different samples at the same risk grade can be reflected in figures. The results not only show high consistency with other assessment methods but are also in good agreement with the excavation results. The proposed cloud model method demonstrates good practical reference for risk assessment of tunnel construction in karst areas and can be applied to tunneling, mining, and other engineering practices in the future.

Classification model for surrounding rock based on the PCA-ideal point method: an engineering application

Scientific classification of rock masses surrounding tunnels has great significance for construction cost and risk in subway systems. Quantifying the surrounding rock simply, quickly, and accurately is always a challenging issue as well as an urgent requirement in construction. Surrounding rock classification considers many complex and variable factors with uncertainty and nonlinear characteristics. Using principal component analysis (PCA) and the ideal point method, a new classification model is built consisting of five key factors, uniaxial compressive strength (UCS), rock mass integrity coefficient (Kv), softening coefficient (η), joint surface coefficient (Jc), and groundwater (ω). In the model, weights of key factors are determined by PCA, then the level of the surrounding rocks is analyzed using ideal point theory. The new model is applied successfully to classify surrounding rock in the Qingdao Metro system. Results provide a reference for classifying surrounding rock quickly and guide the tunnel design and construction.

The numerical simulation on the stability of steep rock slope by DDA

China is a mountainous country, especially in the southwest area. Recently, the variety of geological disasters such as landslides caused by roadway excavation has become a growing concern for our society. Blindly pursuing mining interests without regard for either the environment or residents in the surrounding areas has created a dangerous situation. In recent years, frequent collapses have occurred at Zengzi Rock in Chongqing, especially after torrential rains [1]. This landslide site is a typical example of collapse caused by mine roadway excavations. To study the mechanism of mining slope stability, we conducted a numerical simulation by DDA based on Zengzi Rock in Chongqing, China. The numerical simulation analyzes the slopes under different engineering conditions and rainfall conditions. The results show that the slope has already been changed under the action of its own joints and fissures. After the excavation of the roadway and the rainfall action, this change is drastically increased and the ef...