Influence law of modified glutinous rice-based materials on gravel soil reinforcement and water erosion process

A large number of loose piles formed by mountain hazards are highly susceptible to hydraulic erosion under rainfall conditions.The use of ecological substrate materials for erosion control and ecological restoration of gravel soil slopes has become a current research hotspot and the study difficulty.The post-earthquake slump accumulation gravel soil in Jiuzhaigou was selected as the research object,and the self-developed modified glutinous rice-based material was used to reinforce the gravel soil.The variable slope flume erosion test and rainfall simulation test were carried out to study the water erosion resistance of the material reconstructed soil under the influence of runoff erosion and raindrop splash erosion.The results show that:As the material content reached 12.5%,the reconstructed soil did not disintegrate after 24 hours of immersion,the internal friction angle was increased by 42.26%,and the cohesion was increased by 235.5%,which played a significant reinforcement effect.In the process of slope erosion,the soil rill erodibility parameter Kr was only 3‰ of the gravel soil control group,the critical shear force τ increased by 272%,and the soil erosion resistance was significantly improved.In the process of rainfall and rainfall on the slope,the runoff intensity of the reconstructed soil was stable,and the ability to resist runoff erosion and raindrop splash erosion was enhanced.The maximum value of soil loss rate on different slope slopes is 0.02-0.10 g·m^(-2)s^(-1),which is significantly lower than that of the control group and has better erosion reduction effect.

Mechanisms involved in triggering debris flows,within a cohesive gravel soil mass on a slope:a case in SW China

The triggering mechanisms of debris flows were explored in the field using artificial rainfall experiments in two gullies, Dawazi Gully and Aizi Gully, in Yunnan and Sichuan Provinces, China,respectively. The soils at both sites are bare, loose and cohesive gravel-dominated. The results of a direct shear test, rheological test and back-analysis using soil mass stability calculations indicate that the mechanisms responsible for triggering debris flows involved the decreases in static and dynamic resistance of the soil. The triggering processes can be divided into 7 stages: rainfall infiltration, generation of excess runoff, high pore water pressure, surface erosion, soil creep, soil slipping, debris flow triggering and debris flow increment. In addition, two critical steps are evident:(i) During the process of the soil mass changing from a static to a mobile state, its cohesion decreased sharply(e.g., the cohesion of the soil mass in Dawazi Gully decreased from 0.520 to0.090 k Pa, a decrease of 83%). This would have reduced the soil strength and the kinetic energy during slipping, eventually triggered the debris flow.(ii) When the soil mass began to slip, the velocity and the volume increment of the debris flow fluctuated as a result of the interaction of soil resistance and the sliding force. The displaced soil mass from the source area of the slope resulted in the deposition of a volume of soil more than 7-8 times greater than that in the source area.

Effect of clay content to the strength of gravel soil in the source region of debris flow

The production of runoff in the source area of a debris flow is the consequence of a reduction in soil strength. Gravel soil is widely distributed in the source region, and the influence of its clay content on soil strength is one of the important questions regarding the formation mechanism of debris flows. In this paper, the clay content in gravel soil is divided into groups of low clay content(1%, 2, 5%), moderate clay content(3.75%, 5.00%, 6.25%, 7.5%) and high clay content(10.0%, 12.5%, 15%). Tests of the unconsolidated undrained shear strength and consolidated drained shear strength were performed. The unconsolidated undrained shearing(UU) experiment simulates the rapid shear failure of loose gravel soil under the conditions of brief heavy rainfall. The consolidated drained shearing(CD) experiment simulates creep failure of consolidated sediment during extended rainfall. The pore water pressure first increased and then decreased as the clay content increased, and the increase in pore pressure was relatively high in the gravel soil sample when the clay content is in the range of 3.25-7.50%, and stress in the gravel soil is relatively low for a moderate clay content. Gravelly soils with a moderate clay content are moreprone to debris-flow initiation. This paper presents a mathematical formula for the maximum shear stress and clay content of gravel soil under two conditions. The key processes whereby the soil fails and triggers a debris flow—volume contraction of soil, expansion of clay soil, and rise of pore pressure―cause reductions in the soil friction force and enhancement of the water content in the clay particles, and subsurface erosion of soil reduces the soil viscosity, which eventually reduces the soil strength so that the soil loses its stability, liquefies and generates a debris flow.

Numerical Analysis on Soil and Rock Formation of Ancient Gravel Strata Around Nanjing

Research samples were taken from an ancient gravel stratum which is not only a representative soil layer along the middle-lower reaches of the Yangtze River in East China, but also one of the primary Neozoic strata in Naming district. Located mostly on the second and third terraces, the ancient gravel strata formed the geomorphic landscapes of terrace and step. They were complex in constitution, varied widely in stability, of multiple sources, locally derived, and associated with braided streams in the deposition environment. A CIPW (Cross, Iddings, Pirsson and Washington) method modified by the author was used to analyze the soil-rock-forming materials of finer grains (less than 2 mm in size) of the ancient gravel stratum. Results of the analysis showed that the sandy grains were composed of apatite, ilmenite, potassium feldspar, plagioclase, enstatite and free quartz, the clay mainly of kaolinite, and the cement of a combination of silicon, aluminum and iron at a ratio of 46:44:10. In the soil-rock-forming processes, including compactional solidification, water-stable illuviation-cementation t homogeneous overgrowth and so on, the loose soil-rock-forming components gradually changed into consolidated soil and further to the early stage of lithification. Meanwhile, from the analysis, we found that the ancient gravel stratum had been protected by the overlying Xiashu loess or basalt and the overloading resulted in overconsolidated strata. The modified CIPW method was applicable and effective for semi-quantitative analysis.

Evaluation of the Impact of Truck Overloading on Flexible Compacted Gravel Lateritic Soil’s Pavements by FEM with Cast3M^©

Within the framework of a FEM of the nonlinear behavior of lateritic pavement of Senegal, the effect of truck overloading is studied to estimate its impact on the deformability of road pavement on compacted gravel lateritic soils. For that purpose, various loading conditions were tested to measure the impact on the critical response parameters of road pavement design. The implementation of the models was realized with Cast3M©. This study allowed us to point out that the observed variations are linear and would help to plan in advance the impact of axle overloads for a better evaluation within the framework of the mechanistic (M. E.) design of pavements.

Effects of Different Gravel Mulched Years on Soil Microbial Flora and Physical and Chemical Properties in Gravelsand Mulched Fields

Soil microbial flora and influencing factors of soil microbes in soil and gravel-sand mixed layer（ SGSML）,roots denseness layer（ RDL）,eluviate layer（ EL） and calcium accumulation layer（ CAL） in gravel-sand mulched fields（ GSMFs） with different gravel mulched years（ 1,6,12,19 and 25 years） were studied. The results showed that in the composition of soil microbes in the GSMFs,the quantity of bacteria was the largest,followed by actinomycetes,while the number of fungi was the smallest. The total quantity of soil microorganisms in the GSMFs dropped rapidly with the increase of soil depth,which was related to the sudden decrease in the quantity of bacteria. The number of microbes in the RDL was larger than that in the SGSML with few roots due to the effects of root distribution. The number of bacteria and actinomycete in the growing season was larger than that in the non-growing season,while the quantity of fungi in the growing season was smaller than that in the non-growing season. The quantity of bacteria and fungi was the largest in the GSMFs which had been mulched with gravel for 6-12 years. With the increase of mulching time,the GSMFs aged gradually,so their quantity reduced gradually. The quantity of actinomycetes was the smallest in the GSMFs which had been mulched with gravel for 6-12 years and increased with the increase of mulching time. The number of soil microbes in the GSMFs had a good correlation with soil moisture content,p H and mulching time. Soil total carbon content was an important factor restricting the quantity of soil microbes in the GSMFs.

Grain Size Influence on the Compaction Aptitude and the Bearing Strength of the Gravel Lateritic Soils

This study is carried out to appreciate the coarse elements influence of the gravel lateritic soils on the pavement behavior. The material involves not only the 0/20 mm granular particles considered in the specifications and on the laboratory tests, but also all of the material that is actually used in the construction sites. Geotechnical characterization was leaned on five differentiated granular classes of 0/20;0/25;0/31.5;0/40 and 0/63 mm diameters. The sample of 0/40 mm gets the best compaction aptitude, while that of 0/31.5 mm reaches the greatest bearing strength and a good Optimum Moisture Content. According to the requirements and its bearing strengths, the material is usable up to subbase layer and its behavior depends on the grain size.

砂砾土渗流侵蚀中细粒迁移-沉积-滤通的物理水力临界条件

细粒迁移机制是理解砂砾土渗流侵蚀过程的基础与关键,对研究砂砾土斜坡雨水侵蚀过程的细观致灾机制具有重要意义。目前其运移模式及运移状态发生转变的临界条件并不清晰,不同物理水力条件下的细粒运动类型有所不同。为掌握砂砾土侵蚀过程中细粒的整体运动类型及其发生改变的临界条件,采用可视圆柱入渗试验和离散元数值模拟,分析了细粒迁移的影响因素和内部机理。结果表明:(1)细粒迁移受级配和水力梯度影响显著,而受初始孔隙率影响不显著,且级配的影响大于水力梯度;(2)水力作用下细粒整体运动状态可分为沉积和滤通2种模式,内部结构不稳定的砂砾土细粒运动处于滤通状态,内部结构稳定和稳定性过渡型砂砾土随水力梯度升高细粒的运动状态从整体沉积转变为整体滤通;i=3.4-(3)细粒运动状态在粒径比和水力梯度共同作用下存在明显界限,最终得到细粒沉积-滤通转变的临界条件为0.12e(D15/d85)/1.5。研究可为砂砾土斜坡渗蚀失稳防护提供理论指导。

砾石覆盖下的农田土壤环境效应:研究进展与展望

砾石覆盖是旱区特有的一种保护性耕作模式。长期的农业生产实践已经证明,地表覆砂能够很好地适应旱区严酷、恶劣的自然环境,并为当地农业发展和效益提升带来极大助力。然而,砾石覆盖农田退化所带来的一系列负面效应愈加凸显,成为当地农业发展的障碍因子。文章以砾石覆盖的土壤环境效应为脉络,归纳总结了砾石覆盖对土壤水热环境、土壤盐分、土壤有机质、土壤微生物和酶活性,以及水土保持等方面的影响效应和相关机制。同时,进一步指明旱区砂田当前所面临的问题与挑战,并提出该领域未来可持续深化和拓展的方向,主要包括:(1)砾石覆盖农田退化过程中土壤环境的综合演变机制;(2)“砾石-土壤-作物”系统间的协同作用机制;(3)应对砂田退化的农业修复模式及可持续发展路径;(4)砾石覆盖对局部区域气候的影响机制。

干旱砾漠区不同微地貌单元土壤性状及真菌群落变化特征

探明干旱砾漠区不同微地貌单元土壤性状、真菌群落组成特征及其变化驱动因素,对于该区土壤真菌群落构建机制的理论研究和针对性生态损伤修复策略制定的实践指导具有重要意义。本文首先对比了干旱砾漠区4种微地貌单元(风蚀残丘、砾漠戈壁、河谷和风沙地)土壤理化性质、真菌α多样性及群落组成的变化特征,再结合不同微地貌单元植物群落特性和微气象因子测定,探究了各微地貌单元影响土壤真菌群落的主要生态因子。结果表明:(1)干旱砾漠区土壤均为砂质土壤,其中风沙地砂粒含量最大且黏粒含量最小,而河谷土壤粒径组成则相反;河谷和砾漠戈壁之间土壤容重和有机质含量无显著差异但显著高于其他两种微地貌单元;河谷土壤可溶性盐含量显著低于其他微地貌单元21.4%,但土壤含水量显著高出39.3%;速效养分中除砾漠戈壁的速效氮与速效钾、风蚀残丘的速效磷含量显著较低外,其他微地貌单元速效养分并未表现出显著性差异。(2)土壤真菌α多样性中,Shannon-Wiener指数、Pieloue指数和Simpson指数均表现为在风沙地显著降低而其他微地貌单元差异不明显,但Chao1多样性指数没有显著差异;真菌群落组成在门水平上,不同微地貌单元都以子囊菌门和担子菌门为优势菌门,其中子囊菌门在砾漠戈壁和风蚀残丘优势度最大,担子菌门在河谷占比最大;在属水平上,风蚀残丘的新凸轮孢菌属、暗茎草属,砾漠戈壁的新凸轮孢菌属、光黑壳,河谷的曲霉属、链格孢属,风沙地的金银花属、新凸轮孢菌属分别为各地貌单元土壤真菌群落优势属。(3)土壤含水量、有机质、速效氮、可溶性盐是影响干旱砾漠区不同微地貌单元土壤真菌群落结构变化的共同关键因子,风沙地的土壤机械组成、风蚀残丘的地表温度、光辐射强度、砾漠戈壁的地表风速和河谷的地表植被生物量分别为各自地貌单元影响土壤真菌群落的差异化生态因子。

九寨沟黏性土含量对改良碎石土水分特性的影响

[目的]分析九寨沟2017年“8·8”地震后崩坡积碎石土和当地沉积黏性土不同比例混合体的土壤水分特性,选出适宜研究区植物生长的最佳改良碎石土,为九寨沟地区灾后生态环境修复提供科学依据。[方法]将九寨沟当地黏性土与九寨沟地区碎石土以不同体积比进行混合,通过土水特征曲线试验、水分常数试验、土柱试验来探究不同比例下土壤水分特性,挑选适宜于植物生长的混合土比例。[结果]①van Genuchten模型能够很好地拟合改良碎石土的土水特征曲线,土壤进气值随着黏性土比例的增加而增加,参数α在一定程度上能够表征进气值的状态。②改良后的碎石土使吸湿系数、凋萎系数、田间持水量、饱和含水量等都随着黏性土比例的增加而增加。相较于碎石土,添加黏性土的改良碎石土可用水量增大22.26%~50.00%,最大有效水量增大70.96%~131.46%,更加有利于植物生长。③3种模型对比下,Philip模型对土壤水分入渗模拟效果最好,吸渗率S大小能够在一定程度上代表初始入渗速率的变化趋势。[结论]综合对比不同比例改良碎石土水分特性可见,当下覆土层为储水层,可选择碎石土与黏性土比例为7∶3作为改良碎石土最佳配比;当下覆土层为非储水层,无法储存水分时,可选择碎石土与黏性土比例为3∶7作为改良碎石土最佳配比。

碎石土细颗粒迁移特征及优先流形成路径

碎石土是一种非连续、非均质的结构性材料,由于内部含有大量碎石块,容易形成架空结构,使其内部形成复杂独特的渗流通道即优先流通道,碎石土优先流通道是包括水分运移和土体细颗粒迁移的复杂过程,但在研究其优先流路径时通常只考虑了水分的运移而忽略了细颗粒的迁移,颗粒迁移与通道形成密切相关。为此,对两种不同级配土柱(粗细颗粒连续级配和间断级配)分别进行饱和渗流-颗粒迁移试验,从细颗粒迁移的角度分析通道形成的时空发展规律。试验结果表明:细颗粒迁移一部分由于流失引起碎石土渗透性增大,另一部分由于重新沉积而堵塞局部孔隙,降低渗透性,两者作用结果最终加速优先流通道形成;连续级配的碎石土形成大面积交叉分布的管网状渗流通道,间断级配的碎石土则形成集中渗流通道;相同水力条件下,不同级配细颗粒迁移的空间分布特征不同,连续级配的碎石土细颗粒迁移不随空间位置的差异而发生变化,间断级配的碎石土细颗粒迁移随空间位置的差异而发生变化,两种级配下碎石土细颗粒主要流失量的粒径范围均在1~0.075 mm;不同水力梯度条件下,连续与间断级配试验细颗粒流失量均随水力梯度增加而增大,间断级配的碎石土破坏时水力梯度小于连续级配破坏时水力梯度,间断级配碎石土更容易发生破坏。研究成果为进一步揭示碎石土优先流形成机理提供试验依据。

旱区连作砂田土壤质量和土地生产力演变与调控研究进展

砾石覆盖在改变旱区水文循环和物质转化方面有着至关重要的作用。然而,长期连作给砂田土壤质量及土地生产力带来危机和不确定性。以连作砂田为研究对象,归纳总结了连作年限对砂层质地结构、土壤物理结构、土壤水盐热效应、土壤养分状况、土壤酶活性、土壤微生物特性、作物生长发育以及产量品质的影响效应和可能机制,发现砂田土壤生态环境和土地生产力在人类活动及自然侵蚀的扰动和破坏下整体呈现退化态势,但对不同覆盖条件、施肥水平和种植结构等农田管理措施的响应过程表现出差异性。继而,基于土壤质量和土地生产力的协同和互作效应深入揭示了砂田性能逐年退化机理,并简述了生物、农业及工程调控措施在砂田退化阻控和修复方面的应用进展。在此基础上,提出了砂田退化进程中急需解决的关键科学问题和未来发展方向,主要包括土壤质量演变的基本过程及其发生机制、“砾石-土壤-微生物-植物”系统的叠加和互作效应及其分子机理、土壤改良与生物防治措施的定量化及其调控机制三个方面。在气候变化、植被演替和土地退化背景下,废弃风化砾石的劣化增肥机制及其环境效应将是今后研究的重点。

羧甲基纤维素钠对红海榄幼苗生长和土壤养分的影响

为明确羧甲基纤维素钠(Sodium Carboxymethyl Cellulose,CMC)对沿海困难立地砂砾质土壤的改良作用,以红海榄(Rhizophora stylosa)胚轴为材料,通过室内潮汐模拟试验,研究不同CMC施用量(质量比为1.6%、2.4%、3.2%、4.0%和4.8%)对红橄榄幼苗生长和土壤养分的影响。结果表明,随CMC施用量增加,红海榄幼苗生长量和生物量整体呈先增后减的趋势,均在4.0%CMC处理下最大。与CK相比,不同CMC处理下红海榄幼苗的株高、地径和叶片数分别增加9.78%~38.54%、13.83%~54.31%和20.00%~36.67%;根、茎和叶生物量分别增加10.58%~64.72%、7.97%~36.76%和37.62%~117.99%;土壤有机质、全钾和速效钾含量分别显著增加625.22%~671.96%、147.62%~161.52%和55.56%~77.78%。CMC可促进红海榄幼苗生长,提高土壤养分,可作为沿海困难立地砂砾质土壤的改良剂,推荐CMC施用量为4.0%。

砾石作用下松散红壤堆积体坡面产流产沙特征

为了探究松散红壤工程堆积体在不同降雨条件下的径流产沙特性,基于野外调查统计结果构建堆积体试验槽模型,通过模拟降雨试验研究不同降雨强度下纯土和20%砾石含量堆积体的径流产沙的差异。结果表明:(1)砾石作用延缓堆积体坡面径流发生时间的平均滞后效益为299.56%;2种堆积体径流率随产流历时呈递增变化,随降雨强度增大,平均径流率递增34.48%~244.83%,土石混合堆积体平均径流率相较于纯土减少6.54%~45.83%,平均流速减少13.76%~30.54%。(2)降雨强度≤1.5 mm/min时堆积体侵蚀速率随产流历时总体缓慢递增或趋于稳定,土石混合堆积体平均侵蚀速率比纯土减少80.39%~84.95%;但在强降雨条件下(2.0 mm/min)纯土堆积体侵蚀速率呈快速增大后递减变化,土石混合堆积体侵蚀速率波动递增,且土石混合堆积体平均侵蚀速率比纯土增大20.04%。(3)降雨强度和砾石均会改变堆积体坡面径流产沙和流速,差异显著(P<0.05)且呈“水大沙多”的特点。研究结果可为堆积体水土流失防治措施布设提供指导,为建立工程堆积体土壤侵蚀预测模型提供基础数据。

充填型岩溶隧道仰坡滑塌机制及稳定性控制技术——以宜宾巡场至玉和公路下坝隧道出口段为例

为解决充填型岩溶隧道进洞过程中引起的仰坡滑塌问题,利用现场调查和MultiFracS多物理场断裂分析软件,对隧道进洞过程中仰坡体内裂缝发展过程和围岩变形情况进行分析,提出洞口仰坡加固措施并进行效果评价,得出如下结论:1)连续降雨是引起仰坡滑塌的直接原因,随着含水率的增加,碎石土充填物抗剪强度降低,溶腔区位移变化显著且出现微裂隙;当含水率增加至20%时,溶腔区裂缝进一步发展,局部出现开裂,地表滑动位移不断增加。2)隧道进洞施工扰动加速了地表覆盖层与下伏基岩间贯通裂缝的形成,仰坡体呈现整体滑动趋势。基于现场调查和数值分析,采用“缓坡+钢锚管/锚索框架梁”的仰坡防护形式,用注浆钢锚管替代锚杆和部分锚索,能够避免溶腔内碎石土在雨水下渗中产生变形破坏。经现场实测数据验证,加固后的仰坡在隧道二次进洞过程中处于稳定状态,隧道洞内变形和地表沉降均得到了有效控制。

Frost heave control of fine round gravel fillings in deep seasonal frozen regions

Fine round gravel soil is widely employed in the subgrade of high and thawing. The lower the fines content in fine round gravel soil, but compaction difficulty increases. This study is to obtain the speed railways in cold regions to prevent frost heaving the smaller the quantities of frost heaving and thawing, optimum fines content and limited frost heaving and thawing. The fine round gravel soil filling （FRGSF） used in the Harbin-Qiqihaer Passenger Dedicated Line is taken as the study object. Influence of fines content on optimum water content, maximum dry density and frost heaving properties of FRGSF were studied by means of compaction and frost heaving tests. Results show that the maximum dry density of the FRGSF increases first and then decreases with an increase of fines content, namely there is an optimum fines content for easy compaction. The method of surface-vibratory instrument is fit for coarse-grained soils, and wet state of coarse-grained soil is in favor of compaction. Considering the relationship of fines content with maximum dry density and the frost heaving ratio of FRGSF, the fines content should be limited to within the range of 9%-10%, so that the frost heaving ratio is less than 1%, and the FRGSF is easily compacted. Water supply is proved to be an important factor influencing the amount of frost heaving of FRGSF. We also conclude that in the field, it is imperative to control waterproofing and drainage measures.

滇中引水隧洞砾质土地层盾构渣土饼化控制技术

砾质土地层盾构掘进时,容易发生盾构刀盘结泥饼现象,须对渣土改良参数进行合理优化,以降低结泥饼风险。依托滇中引水龙泉倒虹吸盾构隧洞工程,首先分析砾质土地层盾构结泥饼风险以及分散型泡沫剂发泡性能,然后结合坍落度试验和界限含水率试验探究分散型泡沫改良渣土的塑流性特征,提出砾质土地层盾构渣土饼化风险控制技术,并通过现场跟踪试验对饼化控制技术进行验证。研究结果表明:(1)分散型泡沫剂发泡倍率随着浓度增加而增长,随发泡压力增加呈先增后减趋势,在发泡压力为0.3 MPa时获得最佳发泡倍率;(2)分散型泡沫剂能有效改善砾质土渣土塑流性,降低砾质土渣土液塑限,进而降低渣土饼化风险;(3)提出砾质土渣土改良参数建议值并应用于实际工程,应用后盾构总推力、扭矩明显降低且离散程度减小,盾构推进速度明显提升,验证了砾质土地层盾构渣土饼化控制技术的合理性。

A fundamental procedure and calculation formula for evaluating gravel liquefaction

Field investigations following the 2008 Ms8.0 Wenchuan earthquake identified 118 liquefaction sites, most of which are underlain by gravelly sediment in the Chengdu Plain and adjacent Mianyang area, in the Sichuan Province. Gravel sediment in the Sichuan province is widely distributed; hence it is necessary to develop a method for prediction and evaluation of gravel liquefaction behavior. Based on liquefaction investigation data and in-situ testing, and with reference to existing procedures for sandy soil liquefaction evaluation, a fundamental procedure for gravel liquefaction evaluation using dynamic penetration tests （DPT） is proposed along with a corresponding model and calculation formula. The procedure contains two stages, i.e., pre-determination and re-determination. Pre-determination excludes impossible liquefiable or non-liquefiable soils, and re-determination explores a DPT-based critical N120 blows calculation model. Pre-determination includes three criteria, i.e., geological age, gravel contents, gravel sediment depths and water tables. The re-determination model consists of five parameters, i.e., DPT reference values, gravel contents, gravel sediment depths, water tables and seismic intensities. A normalization method is used for DPT reference values and an optimization method is used for the gravel sediment depth coefficient and water table coefficient. The gravel liquefaction evaluation method proposed herein is simple and takes most influencing factors on gravel sediment liquefaction into account.

青岛地铁土压平衡盾构碎石土改良方法研究

盾构在碎石土地层掘进时经常面临着地层渗透性强、刀盘扭矩大、刀具磨损严重等诸多困难。为解决上述施工难题,以青岛地铁4号线典型的碎石土地层为研究对象,首先通过颗粒筛分、LCPC试验和渗透性试验评价了碎石土的基本特性,结合传统的砂土和黏性土改良方案设计了5组碎石土改良配比方案,对不同配比方案进行坍落度试验、渗透性试验和直剪试验,分析了不同改良指标碎石土的流塑性、渗透性及抗剪力学特性,根据实际工程中盾构刀盘扭矩的变化情况验证了泡沫与聚合物组合改良的最佳方案。研究表明:7%浓度泡沫与5%浓度聚合物配比的改良剂能够有效降低碎石土的渗透系数,同时起到降低刀盘扭矩的作用。