中国石油大厦复合土钉支护现场监测与分析

桩锚与土钉复合支护在国内得到广泛地应用,但其分析理论和设计方法尚欠不足,实践远超过理论。结合北京中国石油大厦深基坑支护工程,介绍了桩锚-土钉复合支护内力的监测方案。通过对复合土钉支护中桩、锚杆、土钉受力的现场测试和分析,研究了桩锚-土钉复合支护各部分的受力机理,对深入认识桩锚-土钉复合支护的受力机理和桩锚-土钉复合支护结构的优化设计提供参考。     

对新型螺杆灌注桩的受力特征与破坏性状的探讨

螺杆灌注桩是一种承载力高、造价低、施工方便、无环境污染的新桩型。根据螺杆桩的静荷载试验资料,深入分析了螺杆桩竖向荷载的传递机理,探讨了螺杆桩的受力特征和破坏性状,为今后螺杆桩的设计和施工提供可靠的依据。     

陕西省地质灾害-气象预报预警系统研制及应用

为了提高地质灾害-气象预报预警工作的自动化程度和产品的质量,文章从计算机系统制作的角度探讨了地质灾害-气象预报预警的方法,论述了陕西省地质灾害-气象预报预警系统的运行环境、软件功能、空间数据库、模型方法等内容,并介绍了陕西省汛期地质灾害-气象预报预警的应用实例。     

神农架大九湖15.753kaB.P.以来的孢粉记录和环境演变*

根据对大九湖297cm厚的泥炭地层10个AMS ¹⁴ C年龄的测定以及148块孢粉样品的分析,发现每块样品的孢粉(浓度)含量都很高,植物种类繁多,分属于137(科)属,可划分为6个孢粉组合带,植被类型演替大体为:含少量常绿树种的针阔叶混交林—含常绿阔叶树种的落叶阔叶林—常绿落叶阔叶林—含常绿阔叶树种的落叶阔叶林—含少量常绿树种的针阔叶混交林。孢粉带Ⅰ(15.753~11.280kaB.P.)记录了该区域晚冰期及其向全新世过渡时期冷暖波动频繁的气候条件,其中亚带Ⅰ -1(15.753~15.549kaB.P.),Ⅰ -3(14.936~14.505kaB.P.)和Ⅰ -5(12.655~11.280kaB.P.)可能分别对应最老仙女木期、老仙女木和新仙女木冷期,而亚带Ⅰ -2(15.549~14.936kaB.P.)和Ⅰ -4(14.505~12.655kaB.P.)分别对应博令和阿勒罗德暖期。孢粉带Ⅱ(11.280~9.218kaB.P.)代表了由晚冰期冷湿气候向全新世温暖气候转换的早全新世缓慢升温的过渡时期。孢粉带Ⅲ(9.218~7.530kaB.P.)代表中全新世前期的气温波动上升期,7.7kaB.P.前后达到最高温。孢粉带Ⅳ(7.530~4.051kaB.P.)代表中全新世适宜期,水热配置条件最佳。孢粉带Ⅴ(4.051~0.911kaB.P.)体现晚全新世温干的气候。孢粉带Ⅵ(0.911~0kaB.P)反映了大九湖温凉稍湿的气候。     

Sulfate Attack on Concrete in an Inland Salt Lake Environment

INTRODUCTIONSulfate attack is one of the reasons for concretestructures deteriorating earlier than usual,thusshowing poor durability.The SO42-from the sur-rounding environment such as ocean,saline,groundwater,and even the concrete itself,reacts with thehydration products of cement,whichleads to the de-terioration of the concrete(Li et al.,2000;Kang,1995;Neville,1983;Samarai,1976).The deteriora-tionincludes three processes:the external swelling,cracking,peeling,and disjointing caused by …     

GZCORS系统的建设与应用

GZCORS覆盖全广州约8000km2的行政区域,它是卫星定位技术、计算机网络技术、数字通讯技术等高新科技多方位、深度结晶的产物,可以全自动、全天候、实时提供覆盖全广州市域的高精度空间和时间信息。对系统建设中的关键性技术问题和具体实施方案进行了研究和解决。     

北京沙河地区地面沉降及抗浮设防水位的探讨

论述了北京沙河高教园区项目在建设中将遇到的地面沉降及抗浮设防水位的确定问题,并提出了相应的解决措施。     

Early cretaceous granitoids and their implications for the collapse of the Dabie orogen, eastern China: SHRIMP zircon U–Pb dating and geochemistry

Two stages of early Cretaceous post-orogenic granitoids are recognized in the Dabie orogen, eastern China, which recorded processes of extensional collapse of the orogen. The early stage granitoids ( 132 Ma) are foliated hornblende quartz monzonites and porphyritic monzogranites. They are of high-K calc-alkaline series and metaluminous to weakly peraluminous, with high K₂O and low MgO contents (Mg^# values: 32.0–46.0), they contain high Sr, low Y and heavy rare earth elements (HREE), and have high Sr/Y and (La/Yb)_N ratios, without clear negative Eu, Sr and Ti anomalies. The early stage deformed granitoids have adakitic geochemical compositions and are equilibrated with residues rich in garnet and poor in anorthite-rich plagioclase, and thus indicate the existence of an over-thickened (> 50 km) crustal root beneath the orogen at  132 Ma. The later stage granitoids ( 128 Ma) are undeformed fine-grained monzogranites, fine-grained K-feldspar granites and coarse-grained K-feldspar granite-porphyry. They belong to a peraluminous and high-K calc-alkaline to shoshonite series, and display a flat HREE pattern and have strong negative Eu, Sr and Ti anomalies, with low Sr/Y and (La/Yb)_N ratios. The late stage granitoids are equilibrated with residues rich in anorthite-rich plagioclase, hornblende, ilmenite/titanite and poor in garnet, indicating that the crust of the Dabie orogen became thinner (< 35 km) at  128 Ma. SHRIMP zircon U–Pb ages and changing compositional trends for these two stages of granitoids indicate that the over-thickened crust formed by the Triassic continental subduction/collision under the Dabie orogen remained until the early Cretaceous, and collapsed quickly in a few million years during the early Cretaceous.     

Experiments on the primary migration of oil from source rocks

Simulation experiments on the primary migration of oil were carried out on massive samples. The results proved that oil generated from source rocks was expelled in the form of an independent oil phase. High oil-expulsion efficiency was observed. It follows that the primary migration of oil is not directly dependent on the quantity of oil generated from the source rocks. Therefore, the oil-expulsion proportion was high though some source rocks yielded only a limited amount of oil. A great deal of gas was produced at the same time of oil-generation. Thus, it can be concluded that the main expulsion energy for oil primary migration came from these gases.