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Identification of abnormal operating conditions and intelligent decision system

Xiuliang LI, Junjie JIANG, Hongye SU, Jian CHU

《机械工程前沿（英文）》 2011年第6卷第4期页码 456-462 doi: 10.1007/s11465-011-0224-0

摘要：

In earth pressure balance (EPB) shield construction, the “plastic flow state” is difficult to form using the soil dug in the capsule because it can cause three abnormal operating conditions, including occlusion, caking in the capsule, and spewing at the outlet of the dump device. These abnormal operating conditions can, in turn, trigger failure in tunneling, cutter-device damage, and even catastrophic incidents, such as ground settlement. This present paper effectively integrates the mechanism of abnormal operating conditions and knowledge of soil conditioning, and establishes a uniform model of identifying abnormal conditions and intelligent decision support system based on the belief rule-base system. The model maximizes knowledge in improving the soil, construction experience, and data to optimize the model online. Finally, a numerical simulation with specific construction data is presented to illustrate the effectiveness of the algorithm.

关键词： earth pressure balance (EPB) shield machine soil pressure cabin abnormal operating condition belief rule-base system

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Hydraulic fracturing pressure of concentric double-layered cylinder in cohesive soil

《结构与土木工程前沿（英文）》 2021年第15卷第4期页码 937-947 doi: 10.1007/s11709-021-0754-4

摘要： This study aims to investigate hydrofracturing in double-layered soil through theoretical and experimental analysis, as multilayered soils where the difference in mechanical properties exists are generally encountered in practical engineering. First, an analytical solution for fracturing pressure in two different concentric regions of soil was presented based on the cavity expansion theory. Then, several triaxial hydraulic fracturing tests were carried out to validate the analytical solution. The comparison between the experimental and analytical results indicates the remarkable accuracy of the derived formula, and the following conclusions were also obtained. First, there is a linear relationship between the fracturing pressure and confining pressure in concentric double-layered cohesive soil. Second, when the internal-layer soil is softer than the external-layer soil, the presence of internal soil on the fracturing pressure approximately brings the weakening effect, and the greater strength distinction between the two layers, the greater the weakening effect. Third, when the internal-layer soil is harder than the external-layer soil, the existence of the internal-layer soil has a strengthening effect on the fracturing pressure regardless of the proportion of internal-layer soil. Moreover, the influence of strength distinction between the two layers on the fracturing pressure is significant when the proportion of internal-layer soil is less than half, while it’s limited when the proportion is more than half. The proposed solution is potentially useful for geotechnical problems involving aspects of cohesive soil layering in a composite formation.

关键词： hydraulic fracturing pressure layered cavity expansion theory triaxial fracturing test cohesive soil

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Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

《机械工程前沿（英文）》 2022年第17卷第2期 doi: 10.1007/s11465-022-0676-4

摘要： The control system presently used in shield posture rectification is based on driver experience, which is marginally reliable. The study of the related theory is flawed. Therefore, a decision-making approach for the deviation correction trajectory and posture rectification load for an earth pressure balance (EPB) shield is proposed. A calculation model of posture rectification load of an EPB shield is developed by considering the interactions among the cutter head, shield shell, and ground. The additional position change during the shield attitude correction is highlighted. The posture rectification loads and shield behaviors results can be solved by the proposed method. The influences of the stratum distribution (i.e., bedrock height in the upper-soft and lower-hard strata) on shield behaviors and posture rectification loads are analyzed. Results indicated that the increase of pitch angle in the upper-soft and lower-hard strata causes a sharp rise in vertical displacement. The bedrock height increases the magnitudes of the required posture rectification moments when h_r/D > 0.5. For a tunnel with h_r/D ≤ 0.5, the variation of h_r/D has little effect on the posture rectification moments. Finally, the posture rectifying curves based on the theoretical model are compared with the target ones based on the double circular arc interpolation method. The required results can be obtained regardless of the soil–rock compound stratum distribution. The maximum rectification moment in the rock layer is almost 12.6 times that in the soil layer. Overall, this study provides a valuable reference for moment determination and the trajectory prediction of posture rectification in compound strata.

关键词： additional position change deviation correction trajectory earth pressure balance shield mechanical model posture rectification

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Experimental study on the stratum applicability and mechanisms of bubble–slurry for earth pressure balance

《结构与土木工程前沿（英文）》页码 1387-1399 doi: 10.1007/s11709-023-0005-y

摘要： Soil conditioning is essential for addressing the stratum applicability problem of earth pressure balance (EPB) shields. Under high water pressures, EPB shields spew water and soil when excavating coarse-grained strata. Typically, foam combined with polymers and slurry is used to solve spewing. However, in current techniques, slurry, foam, and the other agents are mixed with soil separately, their synergistic effect is seldom realized. In this study, an anionic surfactant was used to foam in bentonite slurry to form bubble–slurry to maximize the synergy between bubbles and slurry. The slump, volume stability, and permeability test of bubble–slurry-conditioned sand was conducted to examine the conditioning effect, and the stratum applicability of bubble–slurry was determined from the perspective of permeability. It was found that the conditioning effect of bubble–slurry in coarse gravel soil was excellent and could expand the applicability of EPB shields. The main stabilization mechanism of bubble–slurry is that bentonite particles provide a space barrier for bubbles. And three seepage modes of bubble–slurry-conditioned sand were innovatively defined, and the occurrence conditions of the three seepage modes were analyzed according to the permeability coefficient of sand, initial dynamic shear force of bubble–slurry, and hydraulic gradient.

关键词： EPB shield bubble–slurry soil conditioning stability permeability

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大直径泥水盾构带压进仓地层加固及保压技术

孟海峰,苏清贵,翟志国

《中国工程科学》 2010年第12卷第12期页码 70-74

摘要：

通过对北京铁路地下直径线带压进仓换刀工程实例的分析，探讨了注浆加固及桩基加固在地层加固中的应用，分析了带压进仓的漏气原因并采取相应的应对措施，保证了盾构的正常施工。

关键词：盾构带压进仓保压注浆

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Intelligent technologies help operating mobile cabin hospitals effectively cope with COVID-19

Ying ZHOU, Lingling WANG, Lieyun DING, Zhouping TANG

《工程管理前沿（英文）》 2020年第7卷第3期页码 459-460 doi: 10.1007/s42524-020-0113-5

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论岩土塑性体应变与剪应变的相互作用原理

王靖涛

《中国工程科学》 2006年第8卷第9期页码 24-29

摘要：

对岩土塑性变形过程中体应变与剪应变的相互作用原理的内涵做了深入的阐述，特别对塑性体应变和剪应变之间的相互作用方式，塑性体应变对抗剪能力的直接控制作用，剪缩和剪胀发生的条件，应力路径相关性是这种相互作用的综合体现及实例验证，临界状态是塑性和弹性体应变都保持不变的纯粹剪切变形过程等方面进行了论证；根据这个相互作用原理，在理论上证明了空间临界状态线的存在性和唯一性以及它与应力是无关的。

关键词：岩土塑性体变形和剪应变的相互作用原理岩土本构关系压硬性剪胀性

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Experimental study on concrete box culverts in trenches

Baoguo CHEN, Junjie ZHENG, Jie HAN

《结构与土木工程前沿（英文）》 2009年第3卷第1期页码 73-80 doi: 10.1007/s11709-009-0008-3

摘要： Concrete box culverts are widely used in expressways in mountain areas. Many problems frequently take place due to improperly estimated vertical earth pressures on culverts. The prevailing Chinese General Code for Design of Highway Bridges and Culverts (CGCDHBC) stipulates the computation of the design load on culverts primarily based on the linear earth pressure theory, which cannot accurately describe the variation of the vertical load on culverts in trenches. In this paper, a full-scale experiment and numerical simulation were conducted to evaluate the variation of vertical earth pressures on culvert and soil arching in backfill. The variations of foundation pressure and settlement were also analyzed. The result revealed that the soil arch forms when the backfill on the culvert reaches a certain height. The soil arching effect reduces the stress concentration on the crown of the culvert but it is unstable. The vertical earth pressure on top of the culvert is significantly different from that recommended by the CGCDHBC

关键词： culvert vertical earth pressure soil arch full-scale experiment numerical simulation

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Experimental study of two saturated natural soils and their saturated remoulded soils under three consolidated undrained stress paths

Mingjing JIANG, Haijun HU, Jianbing PENG, Serge LEROUEIL

《结构与土木工程前沿（英文）》 2011年第5卷第2期页码 225-238 doi: 10.1007/s11709-011-0108-8

摘要： In this paper, an experimental investigation is conducted to study the mechanical behavior of saturated natural loess, saturated natural filling in ground fissure and their corresponding saturated remoulded soils under three consolidated undrained triaxial stress tests, namely, conventional triaxial compression test (CTC), triaxial compression test (TC) and reduced triaxial compression test (RTC). The test results show that stress-strain relation, i.e. strain-softening or strain-hardening, is remarkably influenced by the structure, void ratio, stress path and confining pressure. Natural structure, high void ratio, TC stress path, RTC stress path and low confining pressures are favorable factors leading to strain-softening. Excess pore pressure during shearing is significantly affected by stress path. The tested soils are different from loose sand on character of strain-softening and are different from common clay on excess pore water pressure behavior. The critical states in ′– space in CTC, TC and RTC tests almost lie on one line, which indicates that the critical state is independent of the above stress paths. As for remoulded loess or remoulded filling, the critical state line (CSL) and isotropic consolidation line (ICL) in -log ′ space are almost straight, while for natural loess or natural filling, in -log ′ space there is a turning point on the CSL, which is similar to the ICL.

关键词： stress paths static liquefaction natural soil remoulded soil loess structure total strength indices excess pore pressure

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软土机械化隧道开挖——冰积层开挖模式的选择与土壤改良添加剂的运用

Rolf Zumsteg, Lars Langmaack

《工程（英文）》 2017年第3卷第6期页码 863-870 doi: 10.1016/j.eng.2017.11.006

摘要：

高山区地层历史受冰川活动影响，冰川活动对该区域地下工程的影响很大。机械化隧道开挖必须适应可靠和蚀变岩石，必须适应同一条隧道沿线软硬不均土层（透水砾石—软黏土沉积物）。本文主要介绍在瑞士使用隧道掘进机（TBM）的经验，重点介绍穿越软硬不均软土过程中的土壤改良问题。过去大部分隧道均采用泥水模式（SM）掘进，该模式下不同添加剂的使用主要限于高渗透性困难地段和更换工具及改装等需要停止掘进时。对于不太常见的土压平衡模式（EPBM）掘进，连续泡沫改良及额外采用聚合物和膨润土经证明是成功的。调节添加剂的使用使泥浆分离（对于SM）和开挖土料处理（对于EPBM）时面临新的挑战。如果在设计和开挖模式评估阶段提前考虑按符合环境法律规定的方式处理土压平衡（EPB）掘进过程中产生的经化学处理的软土料，则EPBM 有利于冰积层隧道掘进施工。

关键词：土壤改良土压平衡盾构泥水盾构机械化隧道开挖

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DX桩桩周土应力场分布的模型试验研究

唐松涛,陈立宏,袁希雨

《中国工程科学》 2012年第14卷第1期页码 105-112

摘要：

通过室内小比尺的模型试验，可以进一步为确定DX桩沉降计算公式提供必要的依据。在小型模型试验箱中，通过采用杠杆加砝码的装置对22 mm桩径的DX桩在砂土中进行研究，测定单桩的桩顶荷载-桩顶位移曲线，确定承载力，并与相同情况下的直孔桩进行对比；同时，利用微型土压力盒测定土中应力变化，研究荷载在土中的传递规律。试验结果表明，DX桩的承载力及沉降特性明显优于直孔桩；承力盘在上部和下部时，DX桩尽管承载力相差不大，但是盘在下部时会增大桩端附近土体的应力；两个承力盘的DX桩，两盘受力比较一致，且盘受力的影响范围，在竖

关键词： DX桩土压力盒应力量测

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基于纳米光催化的旅客机座舱新型空气净化系统

宁献文,李运泽,王浚

《中国工程科学》 2006年第8卷第4期页码 60-62

摘要：

旅客机座舱空气质量关系到机组成员和乘客的安全、健康和舒适；座舱内空间狭小，人员密集，空气质量与地面建筑环境不同。针对旅客机的座舱环境，提出了基于纳米光催化的新型座舱空气净化系统；与传统的高效过滤器/活性炭复合净化装置相比，纳米光催化装置全寿命期费用非常低，不仅能控制座舱内挥发性有机污染物，还能净化座舱内的微生物，有助于旅客机环境控制系统减小新风量，节省能耗，降低飞机成本。

关键词：旅客机座舱光催化氧化空气净化挥发性有机物活性炭高效过滤器

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Assessment of glass fiber-reinforced polyester pipe powder in soil improvement

《结构与土木工程前沿（英文）》 2021年第15卷第3期页码 742-753 doi: 10.1007/s11709-021-0732-x

摘要： This study investigates the use of glass fiber-reinforced polyester (GRP) pipe powder (PP) for improving the bearing capacity of sandy soils. After a series of direct share tests, the optimum PP addition for improving the bearing capacity of soils was found to be 12%. Then, using the optimum PP addition, the bearing capacity of the soil was estimated through a series of loading tests on a shallow foundation model placed in a test box. The bearing capacity of sandy soil was improved by up to 30.7%. The ratio of the depth of the PP-reinforced soil to the diameter of the foundation model (H/D) of 1.25 could sufficiently strengthen sandy soil when the optimum PP ratio was used. Microstructural analyses showed that the increase in the bearing capacity can be attributed to the chopped fibers in the PP and their multiaxial distribution in the soil. Besides improving the engineering properties of soils, using PP as an additive in soils would reduce the accumulation of the industrial waste, thus providing a twofold benefit.

关键词： shallow foundation sandy soil bearing capacity soil improvement pipe powder

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Electromagnetic induction mapping at varied soil moisture reveals field-scale soil textural patterns

Hiruy ABDU, David A. ROBINSON, Janis BOETTINGER, Scott B. JONES

《农业科学与工程前沿（英文）》 2017年第4卷第2期页码 135-145 doi: 10.15302/J-FASE-2017143

摘要： Knowledge of the spatial distribution of soil textural properties is important for determining soil moisture storage and soil hydraulic transport properties. Capturing field heterogeneity without exhaustive sampling and costly sample analysis is difficult. Our objective was to employ electromagnetic induction (EMI) mapping in low apparent electrical conductivity (EC ) soils at varying soil water contents to capture time invariant properties such as soil texture. Georeferenced EC measurements were taken using a ground conductivity meter on six different days where volumetric water content ( ) varied from 0.11 to 0.23. The 50 m × 50 m field included a subsurface gravelly patch in an otherwise homogeneous silt-loam alluvial soil. Ordinary block kriging predicted EC at unsampled areas to produce 1-m resolution maps. Temporal stability analysis was used to divide the field into three distinct EC regions. Subsequent ground-truthing confirmed the lowest conductivity region correlated with coarse textured soil parent materials associated with a former high-energy alluvial depositional area. Combining maps using temporal stability analysis gives the clearest image of the textural difference. These maps could be informative for modeling, experimental design, sensor placement and targeted zone management strategies in soil science, ecology, hydrology, and agricultural applications.

关键词： soil electrical conductivity soil texture mapping temporal stability analysis

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Combustion instability detection using the wavelet detail of pressure fluctuations

JI Junjie, LUO Yonghao

《能源前沿（英文）》 2008年第2卷第1期页码 116-120 doi: 10.1007/s11708-008-0019-0

摘要： A combustion instability detection method that uses the wavelet detail of combustion pressure fluctuations is put forward. To confirm this method, combustion pressure fluctuations in a stoker boiler are recorded at stable and unstable combustion with a pressure transducer. Daubechies one-order wavelet is chosen to obtain the wavelet details for comparison. It shows that the wavelet approximation indicates the general pressure change in the furnace, and the wavelet detail magnitude is consistent with the intensity of turbulence and combustion noise. The magnitude of the wavelet detail is nearly constant when the combustion is stable, however, it will fluctuate much when the combustion is unstable.

关键词： comparison wavelet approximation pressure transducer general pressure consistent