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DQNN: Pore-scale variables-based digital permeability assessment of carbonates using quantum mechanism-based machine-learning

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Science China(Technological Sciences) 2022年第2期65卷 458-469页

作者： ZHAO Zhi ZHOU XiaoPing qian qihu School of Civil Engineering Wuhan UniversityWuhan 430072China School of Civil Engineering Chongqing UniversityChongqing 400045China State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact PLA University of Science and TechnologyNanjing 210014China

Permeability is a key parameter of rock reservoirs, suggesting the flow characteristics of rock reservoirs. Permeability prediction of carbonate reservoirs is still a great challenge due to its complex pore network and wide range permeability. This work is to establish a digital quantum mechanism-based neural network(DQNN) to study the permeability using the digital porosity,coordination number and pore network size. Experiments and artificial neural network methods(ANN) are applied to validate the accuracy of the proposed DQNN method. In these methods, the pore-scale variables extracted from the micro-CT images of200 carbonate samples are applied. Results show that the permeabilities obtained from experimental, artificial neural network and DQNN methods agree well with each other. Digital pore size, pore throat size and length are better parameters, while coordination number and porosity are relatively secondary parameters for permeability descriptions of carbonate *** with the ANN method, the proposed DQNN method is superior in low computation time and high ability for complicated problems.

关键词： permeability estimation quantum mechanism machine-learning model micro-pore network carbonates

Experimental investigation of rigid confinement effects of radial strain on dynamic mechanical properties and failure modes of concrete

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International Journal of Mining Science and Technology 2021年第5期31卷 939-951页

作者： Pengfei Liu Xiaoping Zhou qihu qian School of Civil Engineering Chongqing UniversityChongqing 400044China School of Civil Engineering Wuhan UniversityWuhan 430072China PLA University of Science and Technology Nanjing 210007China

In this study,to confirm the effect of confining pressure on dynamic mechanical behavior and failure modes of concrete,a split Hopkinson pressure bar dynamic loading device was utilized to perform dynamic compressive experiments under confined and unconfined *** confining pressure was achieved by applying a lateral metal sleeve on the testing specimen which was loaded in the axial *** experimental results prove that dynamic peak axial stress,dynamic peak lateral stress,and peak axial strain of concrete are strongly sensitive to the strain rate under confined ***,the failure patterns are significantly affected by the stress-loading rate and confining *** shows stronger strain rate effects under an unconfined condition than that under a confined *** cracks are created in concrete subjected to uniaxial dynamic compression at a higher strain rate,which can be explained by a thermal-activated *** contrast,crack generation is prevented by *** formulas of the dynamic peak stress and dynamic peak axial strain are established by considering strain rate effects(50–250 s-1)as well as the dynamic confining increase factor(DIFc).

关键词： Strain rate effect Multiaxial loading Dynamic peak axial stress Thermo-activated mechanism Dynamic increase factor

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Introduction

Journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 443-444页

作者： qihu qian PLA University of Science and Technology

At the instigation of some of Emeritus Professor Edwin Thomas(Ted)Brown’s PhD students,a Colloquium in his honour to celebrate his retirement and a long and distinguished career in rock mechanics was held in Brisbane... 详细信息

关键词： Introduction instigation 80th birthday

THE EFFECTS OF THREE-DIMENSIONAL PENNY-SHAPED CRACKS ON ZONAL DISINTEGRATION OF THE SURROUNDING ROCK MASSES AROUND A DEEP CIRCULAR TUNNEL

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Acta Mechanica Solida Sinica 2015年第6期28卷 722-734页

作者： Xiaoping Zhou qihu qian Hanfei Song School of Civil Engineering Chongqing University State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Engineering Institute of National Defense Engineering PLA University of Science and Technology State Key Laboratory of Disaster Prevention & Mitigation of Explosion & Impact PLA University of Science and Technology

In this study, it was assumed that three-dimensional penny-shaped cracks existed in deep rock masses. A new non-Euclidean model was established, in which the effects of penny- shaped cracks and axial in-situ stress on zonal disintegration of deep rock masses were taken into account. Based on the non-Euclidean model, the stress intensity factors at tips of the penny- shaped cracks were determined. The strain energy density factor was applied to investigate the occurrence of fractured zones. It was observed from the numerical results that the magnitude and location of fractured zones were sensitive to micro- and macro-mechanical parameters, as well as the value of in-situ stress. The numerical results were in good agreement with the experimental data.

关键词： deep rock masses containing penny-shaped cracks the non-Euclidean model axial in-situ stress fractured zones zonal disintegration phenomenon deep circular tunnel

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中国盾构隧道工程关键技术的新进展综述

隧道建设（中英文） 2024年第5期44卷 897-926,I0004-I0033页

作者：钱七虎胡小强李树忱陈健竺维彬陆军工程大学江苏南京210007 中国科学院金属研究所辽宁沈阳110016 中国矿业大学江苏徐州221116 中铁十四局集团有限公司山东济南250101 中国铁建水下隧道工程实验室山东济南250101 广州地铁集团有限公司广东广州510330

从研究背景与思路、机制/原理、材料/装备、技术论证、试验研究、工程应用等方面介绍中国大直径盾构掘进主轴承事故分析及国产主轴承的自主研发、盾构隧道工程安全高效掘进渣土适配性改良技术及配套材料、盾尾安全保障核心材料研发、盾... 详细信息

从研究背景与思路、机制/原理、材料/装备、技术论证、试验研究、工程应用等方面介绍中国大直径盾构掘进主轴承事故分析及国产主轴承的自主研发、盾构隧道工程安全高效掘进渣土适配性改良技术及配套材料、盾尾安全保障核心材料研发、盾构隧道新型管片连接技术、城市隧道三模掘进机关键技术等5个方面关键技术的最新进展情况。认为:1)自主研制的超大型盾构机用直径8.01 m主轴承大型套圈纯净度、大型滚子纯净度、大型套圈疲劳性能、大型滚子硬度均匀性、套圈材料淬透性和淬硬层深度、保持架焊缝疲劳寿命和拉断力均优于进口水平;构建了真实对数曲线大型滚子设计方法,突破了高精度大型滚子加工技术,处于国际先进水平,高精度加工和装配保证了零件尺寸精度及形位公差均满足设计要求;通过产品验收、装机应用论证和工程应用,表明应用该大直径主轴承不会产生接触疲劳强度不足和微动引起的疲劳磨损,可用于超大直径盾构隧道工程建设。2)针对黏性、富水砂性和硬岩等复杂地层,以改善岩土环境为核心,研发出了高配向密度的聚合型泡沫剂、高分子抗黏剂、喷涌防止剂和耐磨抑尘剂等环保型系列渣土改良剂,形成了盾构泥饼、喷涌和磨损原位改良主动防控技术,建立了通用地层适配性盾构渣土动态改良技术体系,保障了盾构安全高效掘进。3)针对盾构掘进过程中的盾尾密封失效难题,研发了“黏-稠-流”有机统一的新型盾尾密封油脂,温度敏感性低(黏温系数0.4)、抗水压能力强(最高抗水压3.5 MPa),整体性能提高1.3倍,为盾尾安全提供了有力保障;针对盾构同步注浆浆液泌水、离析和地层沉降难题,研发出了同步注浆充填剂,优化了惰性充填浆液配比,30 min零泌水,实现了壁后惰性充填,保障了管片壁后注浆质量和地层沉降精细化控制。4)新型管片连接技术采用环缝插入+纵缝滑入的连接形式,可以高标准地控制隧道接缝张开量和错台量,管片制作及拼装精度高,可降低接缝防水难度,提升成型隧道的质量,无需设置手孔,无需人工紧固作业,自动化程度高,施工效率高,可节约施工成本及改善洞内拼装作业环境。5)研制出的土压+泥水+TBM三模掘进机能够满足复杂多变、软硬不均复合地层等几乎所有地层的掘进施工,且可在不停机、不拆装设备的前提下实现掘进模式的快速转换,在TBM掘进模式下螺旋输送机+泥浆管道可协同排渣,解决了富水硬岩地层掘进排渣难的问题,机械化和智能化程度高,安全可靠,施工效率高,可改善工人作业环境,节省工期和成本。中国盾构隧道建设取得的巨大成就,推动了中国乃至世界盾构隧道技术的发展和进步,但仍时有安全事故发生,需从装备、材料、技术、管理等方面进一步研究和突破。在今后较长的时间内,中国盾构隧道(尤其是大直径盾构隧道)仍将处于高速建设发展期,面临的建设条件将越来越复杂,技术难度和挑战也将越来越大。要实现盾构隧道建设的快速、安全、健康,需处理好盾构隧道技术领域的关键问题,实现盾构隧道关键核心技术的突破。上述关键技术仍需不断完善并加强推广和应用,以促进中国盾构隧道建设向高适应性、高智能、高可靠性、高效益、高质量、高安全性和低能耗方向发展,形成适合于中国“土壤”的盾构隧道新技术。

关键词：盾构隧道大直径主轴承渣土适配性改良盾尾密封管片连接三模掘进机

THE CONSTITUTIVE RELATION OF CRACK-WEAKENED ROCK MASSES UNDER AXIAL-DIMENSIONAL UNLOADING

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Acta Mechanica Solida Sinica 2008年第3期21卷 221-231页

作者： Xiaoping Zhou qihu qian Yongxing Zhang School of Civil Engineering Chongqing University Chongqing 400045 China PLA University of Science and Technology Nanjing 210007 China

An accurate and efficient numerical method for solving the crack-crack interaction problem is presented. The method is mainly by means of the dislocation model, stress superposition principle and Chebyshev polynomial expansion of the pseudo-traction. This method can be applied to compute the stress intensity factors of multiple kinked cracks and multiple rows of periodic cracks as well as the overall strains of rock masses containing multiple kinked cracks under complex loads. Many complex computational examples are given. The dependence of the crack-crack interaction on the crack configuration, the geometrical and physical parameters, and loads pattern, is investigated. By comparison with numerical results under confining pressure unloading, it is shown that the crack-crack interaction under axial-dimensional unloading is weaker than those under confining pressure unloading. Numerical results for single faults and crossed faults show that the single faults are more unstable than the crossed faults. It is found from numerical results for different crack lengths and different crack spacing that the interaction among kinked cracks decreases with an increase in length of the kinked cracks and the crack spacing under axial-dimensional unloading.

关键词： interaction among cracks axial-dimensional unloading crack-weakened rock masses the stress-strain relation the Chebyshev polynomial expansion

ZONAL DISINTEGRATION MECHANISM OF DEEP CRACK-WEAKENED ROCK MASSES UNDER DYNAMIC UNLOADING

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Acta Mechanica Solida Sinica 2009年第3期22卷 240-250页

作者： Xiaoping Zhou qihu qian Bohu Zhang School of Civil Engineering Chongqing University Chongqing 400045 China PLA University of Science and Technology Nanjing 210007 China School of Civil Engineering and Architecture Southwest Petroleum University Chengdu 610500 China

Size and quantity of fractured zone and non-fractured zone are controlled by cracks contained in deep rock masses. Zonal disintegration mechanism is strongly dependent on the interaction among cracks. The strong interaction among cracks is investigated using stress superposition principle and the Chebyshev polynomials expansion of the pseudo-traction. It is found from numerical results that crack nucleation, growth and coalescence lead to failure of deep crack- weakened rock masses. The stress redistribution around the surrounding rock mass induced by unloading excavation is studied. The effect of the excavation time on nucleation, growth, interaction and coalescence of cracks was analyzed. Moreover, the influence of the excavation time on the size and quantity of fractured zone and non-fractured zone was given. When the excavation time is short, zonal disintegration phenomenon may occur in deep rock masses. It is shown from numerical results that the size and quantity of fractured zone increase with decreasing excavation time, and the size and quantity of fractured zone increase with the increasing value of in-situ geostress.

关键词： deep crack-weakened rock masses interaction among cracks stress superposition principle zonal disintegration mechanism dynamic unloading

THE ZONAL DISINTEGRATION MECHANISM OF SURROUNDING ROCK AROUND DEEP SPHERICAL TUNNELS UNDER HYDROSTATIC PRESSURE CONDITION: A NON-EUCLIDEAN CONTINUUM DAMAGE MODEL

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Acta Mechanica Solida Sinica 2013年第4期26卷 373-387页

作者： Xiaoping Zhou Qinghong Hou qihu qian Yongxing Zhang School of Civil Engineering Chongqing University Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing University Engineering Institute of Engineering Corps PLA University of Science and Technology

A new non-Euclidean continuum damage model is proposed to investigate the zonal disintegration phenomenon of the surrounding rocks around deep spherical tunnels under hydrostatic pressure condition as well as the total elastic stress field *** elastic stress fields of the surrounding rocks around deep spherical tunnels under hydrostatic pressure condition axe *** the elastic stresses of the surrounding rocks satisfy the strength criterion of the deep rock masses,the number,size and location of fractured and nonfractured zones are *** effect of physico-mechanical parameters of the surrounding rocks on the zonal disintegration phenomenon is studied and numerical computation is carried *** is found from numerical results that the number,size and location of fractured and non-fractured zones are sensitive to the physico-mechanical parameters of the surrounding rocks.

关键词： a new non-Euclidean continuum damage model the zonal disintegration phenomenon deep spherical tunnels hydrostatic pressure condition fractured and nonfractured zones the strength criterion of the deep rock masses

STABILITY ANALYSIS OF TWO-DIMENSIONAL LANDSLIDES SUBJECTED TO SEISMIC LOADS

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Acta Mechanica Solida Sinica 2015年第3期28卷 262-276页

作者： Xiaoping Zhou qihu qian Hao Cheng Haipeng Zhang School of Civil Engineering Chongqing University Key Laboratory of New Technology for Construction of Cities in Mountain Areas Ministry of Education Engineering Institute of National Defense Engineering PLA University of Science and Technology State Key Laboratory of Disaster Prevention & Mitigation of Explosion & Impact PLA University of Science and Technology

In the past, the pseudo-static method used to be the most common for evaluating the stability of landslides under seismic loads, in which static forces acting on the center of gravity of a sliding body are used to consider the effects of earthquake. However, seismic loads of rock and soil differ from time and location to time and location. Obviously, it is irrational for the pseudo-static approach to be applied to solving dynamic problems. In this paper, a displacement- pseudo-dynamic model is proposed to assess seismic stability of landslides, in which the sinusoidal- cosinusoidal wave is applied to simulating earthquake displacement, and an ＂amplification factor＂ of peak seismic displacement is referred to as the amplification of seismic wave when it propagates from the bottom to the top of the landslide. The effects of physico-mechanical behaviors of a sliding body on seismic stability of soil slopes are taken into account as well as inertia forces and damping forces. The sensitivity analyses on the permanent displacement and the dynamic factor of safety of landslides are studied in detail. Moreover, a large-scale Tangjiashan landslide that occurred in Wenchuan earthquake is investigated to verify the robustness and precision of the present method. It is found that the results from the present method is in good agreement with those from the previous method.

关键词： pseudo-dynamic factor of safety slices method inertia force damping force sliding displacement displacement-pseudo-dynamic model two-dimensional landslides seismic loads