东莞市石马河流域雁田水凤岗镇非中心区段淤泥污染评价

全面分析石马河流域雁田水凤岗镇非中心区段河道淤泥的污染特征,并对淤泥进行浸出液毒性分析评价;结合淤泥的污染特征情况,提出河道淤泥最终处置建议。

Effect of dry density on the liquefaction behaviour of Quaternary silt

Quaternary silt is widely distributed in China and easily liquefies during earthquakes. To identify the influence of the dry density on the liquefaction behaviour of Quaternary silt, 40 cyclic triaxial liquefaction tests were performed on loose silt(dry density rd=1.460 g/cm^3) and dense silt(rd=1.586 g/cm^3) under different cyclic stress ratios(CSRs) to obtain liquefaction assessment criteria, determine the liquefaction resistance, improve the excess pore water pressure(EPWP) growth model and clarify the relationship between the shear modulus and damping ratio. The results indicate that the initial liquefaction assessment criteria for the loose and dense silts are a double-amplitude axial strain of 5% and an EPWP ratio of 1. The increase in the anti-liquefaction ability for the dense silt is more significant under lower confining pressures. The CSR of loose silt falls well within the results of the sandy silt and Fraser River silt, and the dense silt exhibits a higher liquefaction resistance than the sand-silt mixture. The relationships between the CSR and loading cycles were obtained at a failure strain of 1%. The EPWP development in the dense and loose silts complies with the "fast-stable" and "fast-gentle-sharp" growth modes, respectively. The power function model can effectively describe the EPWP growth characteristics of the dense silt. Finally, based on the liquefaction behaviour of silt, a suggestion for reinforcing silt slopes or foundations is proposed.

潮白河补水过程淤泥污染释放试验及其影响研究

为评价潮白河补水后淤泥对水体的影响,开展了淤泥污染物分析评价,通过室内动态模拟法模拟补水后淤泥的释放通量,预测补水后淤泥对上覆水的影响和预测可能存在的问题。结果表明,重金属内梅罗污染指数显示潮白河淤泥处于重金属清洁状态,而氮磷内梅罗污染指数显示,除潮6—8点位为轻和中污染级外,其他河段处于氮磷重污染级。动态释放模拟法显示,除潮8点位污染释放量较小外,其他点位在补水后均存在污染物大量释放的情况,且存在水黄的风险,主要为类腐殖质类,建议重点关注补水过程中的水质和颜色变化情况,提前采取措施预防风险发生。