海洋通报
海洋通報
해양통보
MARINE SCIENCE BULLETIN
2013年
5期
521-526
,共6页
深水软土%深水沉积物%浅层沉积物%沉积物工程性质
深水軟土%深水沉積物%淺層沉積物%沉積物工程性質
심수연토%심수침적물%천층침적물%침적물공정성질
deepwater soft soil%deepwater sediments%shallow sediments%engineering behaviors of sediments
通过大量试验，对重塑后的南海荔湾深水浅层沉积物的静、动力特性进行了研究，得出以下结论：该深水沉积物的液限与塑性指数高，含水率高，天然容重小；其渗透系数比世界其他深水浅层沉积物渗透系数大1-2个数量级，为2.59×10-7cm/s；此类沉积物属高压缩性、中高灵敏的软土，其固结系数约为1.54×10-3 cm2/s；依据k0固结不排水三轴压缩试验确定的Mohr-Coulomb强度参数预测k0固结不排水三轴拉伸强度，预测结果明显小于试验结果；低频循环荷载作用下，该沉积物的不排水循环强度变化规律与一般饱和软粘土的变化规律一致；地震荷载作用下，尽管它不会发生震动液化，但土层中会产生显著的震动累积孔隙水压力，且破坏时的震动累积孔隙水压力将达到上覆有效压力的90%，这表明地震荷载作用下此种深水沉积物的强度弱化与基础震陷可能是比较明显的。
通過大量試驗，對重塑後的南海荔灣深水淺層沉積物的靜、動力特性進行瞭研究，得齣以下結論：該深水沉積物的液限與塑性指數高，含水率高，天然容重小；其滲透繫數比世界其他深水淺層沉積物滲透繫數大1-2箇數量級，為2.59×10-7cm/s；此類沉積物屬高壓縮性、中高靈敏的軟土，其固結繫數約為1.54×10-3 cm2/s；依據k0固結不排水三軸壓縮試驗確定的Mohr-Coulomb彊度參數預測k0固結不排水三軸拉伸彊度，預測結果明顯小于試驗結果；低頻循環荷載作用下，該沉積物的不排水循環彊度變化規律與一般飽和軟粘土的變化規律一緻；地震荷載作用下，儘管它不會髮生震動液化，但土層中會產生顯著的震動纍積孔隙水壓力，且破壞時的震動纍積孔隙水壓力將達到上覆有效壓力的90%，這錶明地震荷載作用下此種深水沉積物的彊度弱化與基礎震陷可能是比較明顯的。
통과대량시험，대중소후적남해려만심수천층침적물적정、동력특성진행료연구，득출이하결론：해심수침적물적액한여소성지수고，함수솔고，천연용중소；기삼투계수비세계기타심수천층침적물삼투계수대1-2개수량급，위2.59×10-7cm/s；차류침적물속고압축성、중고령민적연토，기고결계수약위1.54×10-3 cm2/s；의거k0고결불배수삼축압축시험학정적Mohr-Coulomb강도삼수예측k0고결불배수삼축랍신강도，예측결과명현소우시험결과；저빈순배하재작용하，해침적물적불배수순배강도변화규률여일반포화연점토적변화규률일치；지진하재작용하，진관타불회발생진동액화，단토층중회산생현저적진동루적공극수압력，차파배시적진동루적공극수압력장체도상복유효압력적90%，저표명지진하재작용하차충심수침적물적강도약화여기출진함가능시비교명현적。
Static and cyclic behaviors of the remoulded deepwater sediments of Liwan in South China Sea were studied by a lot of tests. Following conclusions were obtained The water content, the liquid limit and the plastic index of the sediments were high but its unit weight was low. Its permeability coefficient was 2.59í10-7cm/s and 1-2 magnitude order larger than that of deepwater sediments in other areas of the world. It was the soft sediments with high compression and medium to high sensitivity and its consolidated coefficient was about 1.54í10-3 cm/s. If the undrained triaxial extension strength was predicted under k0 consolidated condition using Mohr-Coulomb parameters determined based on undrained triaxial compression test results under k0 consolidated condition,the predicted results were obviously less than test results. The variation of undrained cyclic strength was the same as that of general saturated soft clays under cyclic loads with low frequency. Although liquefaction did not occur for the soft sediments under earthquake loads, the cyclic accumulative pore water pressure in the stratum would be significant and it might develop to the level of about 90% of the effective overburden pressure when the sediment was failure, which showed that strength degradation of the sediment and seismic settlement of foundation might be obvious under seismic loads.
