循环动荷载下下伏空洞路面塌陷的模型试验研究

在循环动荷载作用下,地下空洞会逐步发展成为路面塌陷。针对此问题,本文建立了模拟路面塌陷发生发展全过程的模型试验。试验结果表明,随着动荷载值的减小,土体所能承受的极限振动循环次数呈指数型增加。而当地下存在一定尺寸的地下空洞时,即使动荷载值较小,在足够多次数的振动循环作用后,也有可能引发路面塌陷。最大粒径较大、不均匀系数较高土体的静力稳定性较强,体现在其能承受的极限静荷载较大;但其动力稳定性较弱,体现在其能承受的极限振动循环次数较少。反之,最大粒径较小、不均匀系数较小土体的静力稳定性较弱,而动力稳定性较强。地下空洞上覆土层厚度越大,则其静力、动力稳定性均较强。同时,循环动荷载作用下地表沉降与土体裂缝的发展呈现出三阶段规律。阶段1为初始固结沉降阶段,持续时间较短,土体受到振动压密作用,地表发生整体沉降,土体裂缝未见明显发展;阶段2为等速沉降阶段,持续时间较长,中心土体受到振动剪切作用,地表中心沉降与土体裂缝随时间呈等速发展;阶段3为加速沉降阶段,持续时间最短,中心土体受到振动破坏作用,地表中心沉降与土体裂缝快速发展直至发生塌陷。     

川藏铁路格聂山和察雅段构造岩溶发育规律及岩溶地下水循环模式研究

Construction of the Sichuan-Tibet Railway may face significant geological safety risks of water inrush and mud inrush in the plateau tectonic karst region. It is of great scientific and practical significance to carry out research on the evolution regularity of the plateau tectonic karst and the relevant karst groundwater circulation mode for the early prediction and identification of the water inrush and mud inrush disaster in the railway tunnel to be built. Based on the field survey and published literatures, this paper makes an in-depth analysis and draws some conclusions. The tectonic karst development shows obvious sequence characteristics and elevation zonation. The first level to fourth level karst development areas were formed before Miocene, late Miocene to Pliocene, Pliocene and Pliocene to Pleistocene, and occur in the elevation range of 4900?5300 m, 4000?4300 m, 3700?3800 m and 2900?3200 m, respectively. Active faults obviously control the distribution and enrichment of karst groundwater. Since the late Pleistocene, active faults have connected different karst areas and formed unique storage conditions for the tectonic karst groundwater in the plateau region. Karst groundwater system can be divided into high recharge area, remote pipeline flow area and concentrated discharge area. The high recharge area occurs in the first-level karst evaluation area, and the third-level and fourth-level are the concentrated discharge area which generally contain the outcropping springs with a discharge of more than 100 L/s. The groundwater system is appropriately divided into shallow and deep groundwater flow system. Karst springs are mainly supplied by ice and snow melting water, and exhibits the dynamic characteristics of the high water pressure, long flow path and deep water groundwater circulation. High CO₂ saturation concentration of the melting water and the salt effect of sulfate promote the formation of high TDS sulfuric acid karst groundwater of low temperature.     

钻井液连续循环钻井技术及自动化装备设计

钻井施工中,拆装钻杆需中止钻井液循环,但钻井液循环中止会导致孔内岩屑下沉、钻井液当量循环密度浮动变化,进而影响孔内安全。为避免上述情况的发生,钻井液不间断循环钻井技术的构想被提出。通过连续循环系统或连续循环接头进行钻井液分流,避开钻杆拆装部分,维持井内的钻井液循环,稳定钻井液当量循环密度。针对该技术原理,提出了一种自动化的钻井液不间断循环井口设备,通过背钳、自动钻井液切换系统和传扭动力卡瓦的配合,可实现钻井中拆卸、接装单根时钻井液不间断循环,有效避免因钻井液静置、沉砂过多导致的钻孔安全问题。     

浅海伸缩套管钻探工艺研究

浅海取心钻探中钻遇易坍塌地层时,需要下放套管封隔地层,保证泥浆循环,换径继续钻进。现有常规下套管方法为使用带有钻台层甲板和套管层甲板的钻井船进行下放套管作业,部分无套管层甲板钻井船在遇到必须下套管的工况时,需临时搭建套管层平台进行下放套管作业,但受钻机和钻具体积及质量的限制。为解决无套管层甲板的钻井船在海洋钻探取心时需要下入套管的难题,设计了一种海洋钻探下入多层套管的工艺方法,利用可伸缩套管及相关设备,在海底井口与小型钻井船之间建立泥浆上返通道,封隔不稳定地层,实现泥浆回收循环及钻具升沉补偿。在钻井过程中,伸缩套管还可以起到导向定位的作用,防止潮差水流流速变化影响钻具下入,为浅海钻井节省时间和成本。     

地热井暂堵型水泥基透水材料的试验研究

地热开采过程中,考虑到水源补给,地热井一般布置在破碎带或构造带上,在钻井过程中利用水泥进行堵漏,但在钻井完毕后为提高产能必须进行解堵。而常规水泥在对地层封堵后需要恢复储层渗透性时,只能通过采取酸化解堵措施,且解堵恢复能力差。如果利用地热开发过程中的温度变化制得可降解暂堵水泥体系,简化地热资源的勘探开发过程,有利于降低钻井成本和风险。本文利用G级油井水泥、砂石、增强剂和水溶性纤维制备温敏型暂堵高透水水泥基材料。通过测试材料的抗压强度、孔隙度、密度、凝结时间,以评价其降解效果及基本性能。结果显示,水溶性纤维的加入使水泥抗压强度明显降低,而增强剂可以稍微改善这一缺陷,90 ℃水浴养护后孔隙度明显高于对照组,并且随着时间的推移,孔隙度不断提升,为水泥基暂堵透水材料成功研制奠定了基础,增强剂和纤维都会减少水泥的凝结时间,纤维降低凝结时间的效果更为明显。该材料的研制将简化地热资源的勘探开发过程,有利于降低钻井成本和风险。     

大菱鲆低温生长遗传参数及相关的估计

The objectives of this present research were to assess the heritability of growth traits under low temperature conditions in turbot(Scophthalmus maximus L.), and to analyze the correlation between body weight(BW) and body length(BL). There were 536 individuals from 25 full- and half-sib families involved in this study. During the entire 90-day period, which was initiated at 233 dph(day old) and ended at 323 dph, the individuals' BW and BL were weighed consecutively six times every 18 days. The heritability of BW and BL and the correlation between these two traits were estimated based on an individual animal model with the derivative-free restricted maximum likelihood(DFREML) method. These results showed that the specific growth rates(SGR) of 25 families was from 0.75±0.11 to 1.05±0.14 under water temperature of 10.5–12°C. In addition, the heritability of BW and BL estimated under low-temperature were 0.32±0.04 and 0.47±0.06, respectively. The BW had a medium heritability(0.2–0.4), and the BL had a high heritability(0.45), which suggested that selection for increased weight and length was feasible. Moreover, there was potential for mass selection on growth. The genetic and phenotypic correlations between BW and BL were 0.95±0.01 and 0.91±0.01(P 0.01), respectively. A significant correlation between BW and BL showed that BL could be instead of BW for indirect selection, which could be effectively implemented in the breeding program.     

高频地波雷达海杂波的边界约束循环对消

在对海洋监视监测的过程中,高频地波雷达的船只目标检测能力与其对海杂波的抑制能力密切相关。但是,传统海杂波时域抑制方法存在目标回波参数与海杂波相近时难以区分其各自分量,对消时目标被误消除的问题。针对上述问题,本文提出了一种适用于高频地波雷达海杂波的边界约束循环对消方法。该方法综合海杂波频移理论和实际海杂波特性分析制定出边界条件,约束建模对消过程,实现海杂波分量的抑制。实测地波雷达数据和船舶自动识别系统(AIS)数据检验的结果表明,本文方法克服了传统方法的不足且信杂比改善更加稳定,能够更加有效地实现海杂波循环对消。     

贵州省24h气温主观预报分析

利用贵州省过去50 a一般观测站资料和过去20 a基本观测数据,统计分析了贵州省各个站点极端高温和极端低温的分布;并统计分析了不同区域不同季节的白天和晚上不同天气状况下的当日最高气温和最低气温之差以及当日最低气温和平均露点温度之差,结果表明:1在贵州地区白天夜晚均为晴天的高低温差四季都在10℃以上,白天为多云的状况下温差次之,白天为阴天和有降水的温差维持在3.0~7.5℃之间;2除了贵州西部春季晴和多云状况下最低温度和露点温差较高外,其余地区随季节和纬度的差异温差保持在0~3.9℃。     

中国大范围持续性极端低温事件的一类平流层前兆信号

本文利用NCEP/NCAR逐日再分析资料,研究了中国大范围持续性极端低温事件(EPECE)的平流层前兆信号及其对对流层环流异常的影响。结果表明,在52个EPECE中,有17个EPECE具有一类共同的平流层前兆信号:(1)在EPECE发生前10天左右,在巴伦支海一带的100 hPa位势高度场呈现较强的正距平特征;(2)随后,该正异常环流逐渐向东移动,并在EPECE发生的前5天左右,使贝加尔湖西北侧200 hPa纬向风显著减弱。本文据此提出了关于EPECE平流层前兆信号的两个判别条件,并以这两个判别条件对1949～2009年冬季(11月至次年3月)所有逐日低频场进行了后查和检验。结果表明,上述两个判别条件对EPECE的发生日期具有一定的预测能力。本文进一步通过位涡(PV)反演探讨了平流层前期异常环流如何影响EPECE发生的物理机制。分析表明,巴伦支海附近的平流层中低层PV异常有利于该地区对流层中上层正高度异常的维持,后者强度的25%来源于前者的作用。     

辽河油田杜84区块超稠油低温氧化反应实验

在模拟注蒸汽条件下,开展辽河油田杜84区块超稠油低温氧化反应实验,分析稠油黏度、SARA组成及气体产物的变化,探讨超稠油低温氧化反应的基本特征和机理.结果表明:杜84区块超稠油经过低温氧化反应后气体产物主要为CO2、CO和余O2,并有少量烃气、SO2和H2S,余氧体积分数一般低于4%.在空气压力为0.25MPa时,超稠油低温氧化反应后黏度增大10%~40%,重质组分体积分数增加5.00%,其中,胶质质量分数降低2.00%~5.00%,沥青质质量分数增大5.00%~10.00%.超稠油低温氧化反应机理主要是芳烃加氧或聚合向胶质转化,胶质加氧或聚合向沥青质转化.