填石路堤动力特性的试验与数值模拟研究

目的为了揭示填石路堤的动力特性，合理设计填石路堤及路面结构．方法通过室内模型试验得到了动力荷载作用下填石路堤内部动应力分布规律以及动力荷载作用后路堤填料颗粒级配变化情况．再采用MARC有限元软件建立了动力荷载作用下填石路堤数值模型，选用Drucker—Prager弹塑性本构模型对填石路堤的动力特性进行了数值模拟．结果有限元可有效模拟动力荷载作用下填石路堤的应力分布规律，而对于填石路堤在动力荷载下的破坏表现为颗粒棱角的破碎以及细粒料漏失的破坏模式，数值模拟则只能采用塑性区表征．结论提出了确定填石路堤动力荷载影响区域的方法，并建议填石路堤上部应设置足够厚的整体性路面结构层次，避免长期汽车荷载作用下因填料棱角破碎和细粒料漏失而发生沉陷的病害．     

土石路堤压实质量控制与碾压动力响应模拟分析

以国道丹阿公路省界(珲春)至东宁段改扩建工程为依托,选取具有代表性的土石混填路堤施工路段,研究得到不同松铺厚度、不同碾压遍数下土石路堤变形与压实特性,采用沉降差控制指标确定以强、中风化凝灰岩为主要填料的土石路堤压实现场施工工艺;同时采用便携式落锤弯沉仪(PFWD)对土石路堤动回弹模量Evd进行检测,将每遍碾压后土石路堤...     

块石压填法处置软土路基的敏感性参数分析

为了更好地评价天然软土路基加固处理效果,采用基于上下负荷面的弹黏塑性本构模型,表征天然软土地基的力学特性,利用大型有限元软件ABAQUS建立模型,模拟路堤分层填筑过程,获取采用块石压填法处置后的软土路基承载力和变形特征。分析了不同块石换填层厚度、变形模量、不同堆载荷载及填筑时长对软土路基的承载力以及工后沉降变形的影响特征。结果表明:基于上下负荷面的弹黏塑性本构模型能够有效地模拟软土路基的变形特征,能用于复杂路基的工后沉降分析;块石压填层的厚度以及变形模量均对地基承载力有显著影响,块石压填层的厚度、填筑时长以及堆载均对工后沉降有显著影响,而块石压填层变形模量并不对工后沉降产生明显影响。     

强夯在威乳高速公路改建工程中的应用研究及一般性推广

旧路改建高速公路会遇到诸如地基不均匀沉降及老路堤压实度低等问题,这些问题限制了这项技术的应用.依托威乳高速公路,研究了强夯在旧路改建高速公路中的应用技术.通过试夯及现场对超静孔隙水压力、动土应力测试及压实度检测,确定了地基与路堤强夯工艺参数.夯后对路堤进行弯沉、回弹测试及路堤沉降观测分析发现强夯方案完全能满足规范要求.最后对威乳路试夯结果进行一般性推广,得到了不同高度路堤对应的止夯标准.     

含泥量对填砂路基动态模量的影响

为掌握含泥量对填砂路基动态模量的影响规律,先通过现场便携式落锤式弯沉仪（PFWD ）试验与压实度试验,分析了含泥量与填砂路基动弹性弹模量的关系;再结合现场检测数据,建立了动态模量随压实度、稠度和含泥量变化的回归模型;最后,结合现场检测与室内PFWD试验结果,提出了填砂路基含泥量的控制标准。研究表明：现场检测路段填砂路基含泥量绝大部分在3．0％～5．5％之间,现场动态模量随含泥量增大而减少,二者具有良好的幂函数回归关系;现场的动态模量与压实度、稠度和含泥量也具有良好的回归关系;当含泥量为0～10％时,随着含泥量的增加,路基动态模量呈先增大后减小的趋势。当含泥量较小（含泥量小于3％）和较大（含泥量大于8％）时,其动态模量要明显小于其他含泥量下的动态模量。当含泥量在3％～8％范围时,动态模量变化幅度较小,故建议含泥量的控制标准为3％～8％。     

Settlement behavior of coal mine waste in different surrounding rock conditions

In order to investigate the influence of complex conditions of in-situ surrounding rocks on the settlement behavior of nubbly coal mine waste subjected to high gravity pressure,four kinds of loading chambers made of different similar materials with different elastic moduli in experiments were used to simulate the deformation features of in-site rocks,including soft,moderate hardness,hard and extra-hard rocks. The results show that all the settlement-axial load （or axial strain-stress） curves obtained under four different surrounding rock conditions present power-exponential function feature. The final settlement of coal mine waste under the same axial load is closely related to the lumpiness gradations and the deformation behavior of chamber materials used to simulate behaviors of different in-situ surrounding rocks. In the same surrounding rock condition,the final settlement under the same maximum axial load decreases with the decrease of the proportion of larger gradation of coal mine waste. While for the same lumpiness gradation case,the settlement increases with the decrease of elastic modulus of simulated surrounding rocks and the lateral pressure induced by axial load increases with the increase of elastic modulus of loading chambers that are used to simulate different surrounding rocks. The test results also reveal that both the compaction curve and lateral pressure curve show a three-stage behavior,and the duration of each stage,which is closely related to gradations and the deformation feature of loading chamber materials,decreases with the increase of the proportion of the small size of coal mine waste and elastic modulus of the simulated rock materials.     

机器人孔口倒角加工振动及抑制

在分析机器人倒角切削振动成因的基础上,提出机器人反向倒角切削振动抑制方法.首先通过构建机器人倒角切削力以及压脚压力作用下的系统动力学模型,对振动成因进行分析,发现在轴向力作用下机器人产生明显动态变形,在径向力与切向力作用下机器人则发生明显强迫振动;进而提出一种机器人反向倒角切削方法,以消除轴向力对机器人的作用,并通过压脚压力的合理选取抑制强迫振动的发生;最后通过机器人正反向倒角对比试验,验证了机器人反向倒角切削的可靠性.试验结果表明：机器人反向倒角切削表面粗糙度小于Ra1.6 μm,孔口宽度差最大为0.05 mm.     

粉性土路堤变形的有限元分析

粉性土路堤在不同行车荷载、不同压实度、不同填筑高度下的变形和应力有限元计算结果表明:超限车辆引起粉性土路堤的过大变形是导致半刚性沥青路面结构疲劳开裂的重要因素.路堤填筑高度大于8m后,路堤内的应力应变急剧加大,大大超过路基顶面的容许弯沉.提高粉土路基的压实度,特别是提高90 % ,93%区的压实度能有效地降低路基的变形,改善路面结构的疲劳拉应力状况     

Die wall lubricated warm compaction behavior of non-lubricant admixed iron powders

The phenomena of die wall lubricated warm compaction of non-lubricant admixed iron powders were researched, and its mechanism of densification was discussed. Water atomized powder obtained from the Wuhan Iron and Steel Corporation was used. With compacting and sintering, compared with cold compaction, the density of warm compacted samples increases by 0.07-0.22 g/cm 3 at the same pressed pressure. The maximum achievable green density of warm compacted samples is 7.12 g/cm 3 at 120 ℃, and the maximum sintered density is 7.18 g/cm 3 at 80 ℃. Compared with cold compaction, the ejection force of warm compaction is smaller; the maximum discrepancy is about 7 kN. The warm compacted mechanism of densification of iron powders can be obtained: heating the powder contributes to improving plastic deformation of powder particles, and accelerating the mutual filling and rearrangement of powder particles.     

Effective depth of dynamic compaction in embankment built with soils and rocks

Effective depth of dynamic compaction was summarized, and the advantages of dynamic compaction technology of effective depth were analyzed elaborately. The formula determining the reinforcement depth was deduced by using dimensional analysis method. The influential factors of hammer weight, hammer area, dry density of filling materials and filling materials types were comprehensively investigated. The formula of effective depth was established based on the definition of the dimensions analysis. Based on exp...     

预应力路堤附加围压场与围压增强效应

利用ABAQUS建立预应力路堤（PE）三维有限元模型，以侧压板（LPP）宽度1.2 m，边坡坡率1∶1为例，分析其内部附加围压场的分布特征. 结果表明：随距路堤坡面水平向深度增加，板体覆盖侧附加围压由浅层 “腹鼓形”差异分布逐渐过渡至深部的较均匀分布；板体3个外延区的附加围压均随坡面水平向内深度先增后减，以不同峰值围压扩散角将预应力扩散至路堤受荷核心区，且峰值扩散角依次为：板外上侧<板外左、右两侧<板外下侧. 基于强度折减法，分析预应力路堤整体稳定性能，并探寻板间距的优化设计方法和思路. 开展典型路堤填料的系列静动三轴试验，论证预应力加固结构能有效提高填料的静动力抗载和抗变形性能，并建立填料临界动应力与围压间的经验式，可以为补强铁路路堤土围压提供参考.     

A roof model and its application in solid backfilling mining

Through changing the axial load on backfilling material compaction test to reflect different overlying strata pressure on backfilling material, the stress-strain relations in the compaction process of backfilling material under the geological condition can be obtained. Based on the characteristic of overlying strata movement in backfill mining, a model of roof thin plate is established. By introducing the stress-strain relation in compaction process into the model and using RIZT method to analyze the bending deformation of roof, the bending deflection and stress distribution can be obtained. The results show that the maximum roof subsidence and maximum tensile stress occurring at the center are 255 mm and5 MPa, respectively. Tensile fracture of roof under the geological condition of Dongping Mine did not occur. The dynamic measurement results of roof in Dongping Mine verify the theoretical result from the aforementioned model, thereby suggesting the roof mechanical model is reliable. The roof thin plate model based on the compaction characteristic of backfilling material in this study is of importance to research on backfill mining theories and application of backfilling material characteristics.     

废旧轮胎片体-风化料混合物压实特性的试验研究

为了推进废旧轮胎在土木工程中的应用,选择废旧轮胎片体(tire derived aggregates, TDA)与分布广且价格低的风化料混合形成混合料,并用TDA在混合料中以0~60%的掺量,通过大尺寸击实设备开展重型击实试验,研究废旧轮胎片体-风化料混合物的压实特性。试验结果表明,混合料的击实曲线与纯风化料的击实曲线有明显差异,增加废旧轮胎片体的掺量能够有效减小混合料的最大干密度,能减小混合料的最优含水率,废旧轮胎片体-风化料混合物是一种性能优良的轻质填料。根据室内试验结果,TDA掺量为20%时,混合料的最大干密度和最优含水率分别为1.865 g/cm³和6.25%;TDA掺量为40%时,混合料的最大干密度和最优含水率分别为1.600 g/cm³和4.90%,给出了不同掺量混合料击实指标建议值供设计参考。     

Die wall lubricated warm compaction behavior of non-lubricant admixed iron powder

The phenomena of die wall lubricated warm compaction of non-lubricant admixed iron powders were researched, and its mechanism of densification was discussed. Water atomized powder obtained from the Wuhan Iron and Steel Corporation was used. With compacting and sintering, compared with cold compaction, the density of warm compacted samples increases by 0.07 - 0. 22 g/cm^3 at the same pressed pressure. The maximum achievable green density of warm compacted samples is 7.12 g/cm^3 at 120℃, and the maximum sintered density is 7.18 g/cm^3 at 80℃. Compared with cold compaction, the ejection force of warm compaction is smaller; the maximum discrep- ancy is about 7 kN. The warm compacted mechanism of densification of iron powders can be obtained： heating the powder contributes to improving plastic deformation of powder particles, and accelerating the mutual filling and rearrangement of powder particles.     

海堤填筑料固结特性研究

试验以海泥,山土,10%、15%、20%三种水泥掺量的海泥搅拌水泥(桩)土作为海堤填筑料。从固结特性方面研究出最适用于海堤填筑的材料,通过基本物理力学性质试验和标准固结试验获取试样的基本物理力学参数、压缩系数和固结系数,再从固结压缩变形和固结速率的角度对试样作出分析。结果表明:(1)天然海泥压缩变形最大,固结速率最小。(2)天然山土的压缩变形最小,但固结速率低于海泥搅拌水泥(桩)土。(3)随着水泥掺量的增加,海泥搅拌水泥(桩)土的压缩变形最小,相比海泥、山土,固结速率也最小,但水泥掺量对海泥搅拌水泥(桩)土的固结速率影响不大。故从固结特性角度得出,水泥掺量为20%的海泥搅拌水泥(桩)土是最适用于海堤填筑的材料。     

水泥稳定碎石振动与静压成型物理力学指标关系

为了明确振动和击实(静压)成型方法对水泥稳定碎石基层材料的物理、力学性能的影响,明确强度差别产生的原因,采用振动成型仪对水泥稳定碎石进行振动成型,测定物理力学指标,并与击实(静压)成型试件的性能进行比较．试验表明振动成型水稳碎石的最佳含水量和最大干密度与击实成型具有线性关系,振动成型下的最大干密度与击实成型相比平均提高0.04 g/cm³,增加的幅度在1.8％左右;振动成型总体强度比静压成型提高70％,其中60％的强度增加量源在于骨架的嵌挤作用;基于强度等效原则,可节约水泥质量2％～3％; 按级配类型回归曲线的斜率表征级配类型对工艺的适应性,截距表征了级配的在强度方面的优劣．研究表明,振动的成型对于无机结合料集料类基层材料,其优越性不仅仅在于提高密度,更在于其对于级配结构性作用的提高,使材料的级配效应得到充分发挥．     

最大承载力状态下全风化花岗岩路基变形特性与控制方法

为了研究南方湿热条件下全风化花岗岩填筑路基的科学方法,以提高路基在运营期的耐久性与稳定性,对全风化花岗岩进行了湿法重型击实与加州承载比试验。结果表明:承载力最大状态下全风化花岗岩的含水率比最佳含水率更接近天然含水率。为进一步了解其湿胀特性,通过改变初始含水率进行了膨胀率试验,得到了全风化花岗岩在不同初始含水率下的干密度衰变规律;通过改进的固结试验对比分析了全风化花岗岩在最大承载力和最大干密度状态时的变形特性。结果显示:与常规的以最大干密度控制方法相比,全风化花岗岩在最大承载力状态下抗变形能力和稳定性更好。按最大承载力状态铺筑了全风化花岗岩路基试验段并进行了现场回弹模量和压实度检测,结果表明:最大承载力状态下全风化花岗岩路基完全能满足下路床94区的压实要求,为了满足路面对路基回弹模量的要求,基于变形等效原理提出刚度补偿设计方法,以确保全风化花岗岩路基整体刚度与耐久性。     

考虑颗粒破碎的堆石料动力变形特性模拟

颗粒破碎是影响堆石料强度和变形特性的重要因素,但目前针对颗粒破碎的模拟研究多在静力荷载条件下。为研究颗粒破碎对小应变条件下堆石料的动力变形特性的影响,采用多个等粒径小球按最密六方排列随机组合模拟不规则形状的堆石颗粒,通过碎片替换法模拟颗粒破碎,研究了花岗岩堆石料不同围压下的动力响应,探索了孔隙率对动弹性模量的影响,分析了振动过程中的颗粒破碎规律及配位数的频率分布。结果表明模拟的骨架曲线与室内试验结果具有较好的一致性,数值模拟可以较好地再现不同围压下堆石料的动力变形特征。在相同围压和动应力条件下,考虑颗粒破碎的试样会产生更多不可恢复的变形,动应变会明显增大,动弹性模量降低。振动过程中集合体的有效配位数会减小,与不考虑颗粒破碎的情况对比,考虑颗粒破碎的试样具有更多的力学不稳定颗粒,有效配位数的降低更显著。颗粒破碎对最大动弹性模量的影响较小,但会加快动模量随动应变增长而衰减的速率。孔隙率小的试样有效配位数高,且受力性能更好。在相同动应力条件下颗粒破碎较少,动弹性模量随动应变的增加而衰减的速率较慢,最大动弹性模量约为大孔隙率试样的1.2倍。最大动弹性模量主要与有效平均主应力和孔隙率相关,Hardin等提出的经验公式可以较好地描述最大动弹性模量与孔隙比和平均有效主应力的关系。该成果有助于认识粗粒料动荷载下的变形规律,为研究动荷载下的颗粒破碎行为提供参考。     

软岩改良土特性的室内试验研究

研究基于对石灰和水泥改良土强度形成机理的分析，开展了软岩改良土大量的室内实验研究，将生石灰和水泥分别按不同比例，与不同含水量的软岩人工拌和均匀，进行击实试验，确定最大干密度和最佳含水率，比较不同掺灰量、不同龄期、不同压实度改良土的无侧限抗压强度，并根据生石灰和水泥的加固机理，进一步分析改良土密实度随掺灰比变化的规律，以及其强度与掺灰比、龄期、压实度的关系，从而确定改良方法及最佳掺灰比，旨在为客运专线路基的设计、施工进一步的研究和工程应用提供参考。     

Effect of expansive fillings on fracture seepage

Based on an investigation of the damage process of fractures filled with expansion media, samples of filling media col-lected on the spot, were obtained. The physical water properties of fracture fillings were tested by a WZ-2 type Dilatometer. Given our test results of the hydrated properties of fracture fillings and the mechanical parameters of altered rock mass collected from the Daye Iron Mine and comparisons between the expansion stress of fracture fillings and mechanical parameters of altered rock mass, the effects of the mechanical response of fillings on fracture seepage are discussed. The results show that the ratio of filling swell pressure to tensile strength of altered rock specimen varied between 11.79 and 36.77 and the ratio of filling swell pressure to shear strength of these rock specimen ranged from 72.11 to 171.18. Therefore, fillings have an important effect on fracture seepage, and the effect of deformation of the fracture caused by swell pressure of the filling mechanics cannot be ignored either. The multiple hydraulic coupling effects of fillings on the impact of fracture permeability are discussed according to theoretical analyses. It is shown that the effect of expansion of fracture fillings greatly affects the deformation of altered rock masses. Both tensile effect and shear effect produced by fracture fillings greatly increase the permeability of fractures. The plastic and liquefaction effects of frac-ture fillings also improve the permeability of fractures. On the basis of this analysis, a mechanical seepage model of filled fracture is established.