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通过青岛保税区地基强夯试验，观测分析了区内海相沉积含砂淤泥质土在夯击能量作用下垂向及水平方向的变形及孔隙水压力产生、消散规律，对区内软土地基可夯性进行评价分析。试验结果对沿海地区淤泥质土加固处理具一定的借鉴意义 相似文献
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马永峰 《中国海洋大学学报(自然科学版)》2018,(7)
依托广西钦州港区某大型工程软土地基处理实践,开展8 000和15 000kN·m能级强夯置换处理软土地基的现场试验;基于强夯置换过程中超孔隙水压力测试、强夯置换前后多道瞬态面波测试及重型动力触探试验、强夯置换后钻孔检测及静载试验结果,对地基承载力和土体工程特性变化进行详细分析。研究结果表明:2个能级强夯置换后,地基承载力均明显提高,土体工程特性得到改善,置换后复合地基承载力均大于200kPa,变形模量分别大于20和15 MPa,满足地基处理设计要求;8 000和15 000kN·m能级强夯置换第1遍强夯超孔隙水压力消散时间分别为6~7d和为7~8d;8 000和15 000kN·m能级强夯有效加固深度约为8.0和9.5m,水平振动影响安全距离约为18.0和25.0m;强夯置换后,置换墩体与墩间土间存在明显的不均性,设计时应充分考虑到强夯置换后地基土的不均匀性。 相似文献
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在青岛娄山河污水处理厂使用强夯法对粉煤灰地基进行处理,通过定量计算分析强夯前后土工试验、原位测试结果,评价粉煤灰物理力学性质的改善状况;分析原位测试试验成果之间的内在联系,对强夯法加固粉煤灰地基的效果评价进行了初步研究。结果显示,强夯有效加固深度内的粉煤灰层物理力学性质发生了明显改善,但其孔隙比仍大于1.0;点夯过程宜及时排水,以提高夯实效率。本文研究结论对粉煤灰地区的加固具有一定的指导和参考意义。 相似文献
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以黄河口海底粉土为研究对象,利用自行研发的监测设备现场监测了波浪作用下海底粉土的孔隙水压力响应过程,获取了2个大风过程中孔隙水压力的有效数据。波浪作用下海底粉土的孔隙水压力响应由表层土最先开始,向下层土延伸,且响应程度随着土层深度的增加而减弱。孔隙水压力响应特征受潮位与波高影响明显,潮位影响孔隙水压力响应的整体趋势而波高影响孔隙水压力响应的幅值,且海底粉土孔隙水压力对波高的响应具有滞后性,滞后时间约为2 h。大风过程中海底面以下1.5 m以深孔隙水压力未发现明显变化,说明其超过了波浪最大作用深度;海底面以下0.5 m位置处孔隙水压力在一段时间内产生剧烈振荡,无明显的累积现象,说明其处于波浪作用范围内,但波浪作用导致的孔隙水压力小于土体孔隙水压力的消散速率。 相似文献
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以黄河口海底粉土为研究对象,利用自行研发的监测设备现场监测了波浪作用下海底粉土的孔隙水压力响应过程,获取了2个大风过程中孔隙水压力的有效数据。波浪作用下海底粉土的孔隙水压力响应由表层土最先开始,向下层土延伸,且响应程度随着土层深度的增加而减弱。孔隙水压力响应特征受潮位与波高影响明显,潮位影响孔隙水压力响应的整体趋势而波高影响孔隙水压力响应的幅值,且海底粉土孔隙水压力对波高的响应具有滞后性,滞后时间约为2 h。大风过程中海底面以下1.5 m以深孔隙水压力未发现明显变化,说明其超过了波浪最大作用深度;海底面以下0.5 m位置处孔隙水压力在一段时间内产生剧烈振荡,无明显的累积现象,说明其处于波浪作用范围内,但波浪作用导致的孔隙水压力小于土体孔隙水压力的消散速率。 相似文献
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单桩基础周围斜坡海床中的波致孔隙水压力响应与纯斜坡海床存在较大差异。为了解不同波高、波周期条件下,单桩基础周围波浪传播变形及其对斜坡海床孔压振荡响应的影响,在波浪水槽末端铺设了长6 m、坡度1∶16的斜坡砂床进行试验。通过改变桩身位置和波浪参数,测量斜坡段各处波面形态,采集单桩周围孔隙水压力,分析了桩身位置及波浪参数对斜坡海床孔压响应的影响。结果表明：相同入射波条件下,随距坡脚水平距离增加,波高、近底流速和桩周孔隙水压力幅值都随之增大;桩周孔隙水压力幅值分布规律为：桩前孔压幅值明显大于桩侧与桩后孔压幅值。当Keulegan-Carpenter数大于6时,随着波高和波周期增大,马蹄涡产生的负压区使得桩侧海床孔隙水压力与纯斜坡海床孔隙水压力差值迅速增加。 相似文献
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内孤立波浅化破碎过程斜坡沉积物孔压响应特征实验分析 总被引：2，自引：2，他引：0
观测资料显示内孤立波沿斜坡浅化过程对海底沉积物的作用犹如一台水中吸尘器，在破碎转换阶段达到最强，甚至会触发一系列地质活动，引发地质灾害。为界定此过程中沉积物的动力响应特征和影响因素，在大型重力式分层流水槽中模拟不同振幅内孤立波和不同类型沉积物斜坡连续作用过程，利用孔隙水压力采集系统实时记录孔隙水压力变化，对比分析不同水动力、坡度、沉积物类型情况下沉积物中超孔压变化特征。分析结果表明，内孤立波破碎过程，破波位置海床表层波压力和不同深度超孔隙水压力都存在相似的"U"型负压力变化过程；破碎波经过位置沉积物表现为和表面波压力正相关的孔压响应特征。破碎点沉积物中超孔压幅值随深度减小，约在6%波长深度位置减少到坡面压力的50%。超孔压幅值和内孤立波振幅、沉积物类型和斜坡度密切相关，坡度由0.071变化到0.160时，波压力幅值可增大至1.6倍。内孤立波振幅变化不影响不同类型海床土动力响应规律，只与超孔隙水压力值大小有关，内孤立波对海床的动力作用可认为弹性作用。 相似文献
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强夯在粉煤灰地基处理中的应用 总被引：1，自引：0，他引：1
粉煤灰海水湿排造陆是沿海地区粉煤灰利用的主要途径之一。但造陆以后属于软土地基，不能直接利用，必须对其进行地基处理，处理效果如何，需进行评价。本文研究强夯处理在青岛沿海粉煤灰排放区的应用，并采用载荷试验、圆锥动力触探试验、室内实验等多种方法对强夯处理效果进行检测。检测结果表明，强夯处理后粉煤灰地基土能够达到设计的150kPa要求，为海水湿排粉煤灰造陆地基处理方法的应用和处理效果检测提供了借鉴。 相似文献
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不同软基处理方法适用性比较 总被引：8，自引：0，他引：8
总结分析了国内外现有的软土地基处理的各种方法。通过对采用不同方法进行软基处理的工程实例处理效果的定量对比，发现不同软基处理方法的适用性差异很大，多数工程中仅用一种方法很难达到设计要求，而两种或多种方法联合则可望取得更好的效果。 相似文献
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Marine deposit ground usually need significant improvement before the construction of civil structures in coastal areas due to the poor mechanical properties of soils. Dynamic compaction (DC) is a widely used technique in such projects. In this study, a case history of DC tests in sandy soils with a weak embedded layer is introduced. Two series of DC tests—single point tests and impact zone tests—were applied to test zones with similar geological conditions to investigate the effect of energy level on the depth of improvement (DI). The highest energy used is up to 15000 kN · m. Field measurements were conduct before and after DC in each series to validate the effectiveness of improvement, including crater settlement, excessive pore pressure, and acceleration measurement for single point tests, and the pressure meter and CPT tests for impact zone tests. For single point tests, the effectiveness of improvement increases as the energy level increases to 12000 kN · m. Further increase of compaction energy does not have an effect on settlement, pore pressure, or ground acceleration. For impact zone tests, the energy level does not show a positive correlation with the DI, mainly due to the presence of an embedded weak layer. 相似文献
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Shi-Jin Feng Wei-Hou Shui Li-Ya Gao Li-Jun He 《Marine Georesources & Geotechnology》2013,31(2):130-142
High energy dynamic compaction (HEDC) is adopted in a coastal reclamation area because the grain size of backfilled soil mostly ranges between 20 cm and 100 cm. The in situ tests for evaluating the effectiveness of HEDC were performed on the backfilled soil ground. The crater depth per drop and the whole test zone elevations before and after HEDC were measured and analyzed. Dynamic penetration tests and spectral analysis of surface wave (SASW) tests were used for investigating the improvement depth. Furthermore, the allowable bearing capacity of HEDC treated ground was determined based on the results of plate-load tests. It was found that HEDC did not cause the ground surface heave during construction, and was more effective than low energy dynamic compaction (LEDC) in terms of applied energy utilization. Based on the test results, the improvement depth of HEDC at this site was not less than 14 m, and there was no obvious weak layer within the range of improvement depth. The allowable bearing capacities were larger than 160 kPa. The investigation results indicate that the HEDC technique is an effective way for improving backfilled coarse-grained soil in coastal reclamation areas. This technique helps to achieve both greater improvement depths and higher ground bearing capacities as compared with LEDC. 相似文献
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In this paper, a case study was performed on a sand compaction pile (SCP) and a gravel compaction pile (GCP) to estimate the dynamic characteristics and the improvement effect of soft ground. The dynamic elastic modulus, shear modulus, bulk modulus, and Poisson's ratio were estimated and the dynamic characteristics were analyzed using the compression and shear wave velocity of the improved ground based on the results of suspension P- and S-wave (PS) logging. The results revealed that the dynamic properties were increased in the order of unimproved subsoil and improved subsoil using SCP and GCP. The increase in the effects of dynamic properties with each replacement ratio of SCP was not large, whereas a good increase in the effects was observed in the case of the improved subsoil with GCP. Consequently, it was presented that the resistance characteristics against the seismic loading of GCP are excellent. As a result of analyzing the density distribution of the improved subsoil through density field logging, the overall density distribution gradually exhibits increasing trends in the order of unimproved subsoil and improved subsoil with SCP and GCP. Thus, the improvement effect of GCP was relatively high in comparison with the same replacement ratio of SCP. 相似文献