Application of SPAC method and electromagnetic wave CT in karst detection of Wuhan Metro Line 8

In recent years,karst construction projects in the built-up area of Wuhan(capital of Hubei Province,China)are increasing,and the karst geological disasters have aroused social concerns.The actual engineering projects usually use shallow geophysical exploration methods to explore karst.This paper uses Spatial Auto-Correlation Method(SPAC)and electromagnetic Computerized Tomography(CT)to detect karst in urban built-up areas.Depending on the different physical properties of rock and soil,the SPAC method can better reveal the interface between soil and rock strata and the interface between soil layers.The electromagnetic CT method can identify strata according to the apparent absorption coefficient,which can better reveal the interface between soil and rock,the interface between the more intact and weathered rock.The SPAC method is mainly qualitative to measure the low-speed area,namely,the wrong geological body i.e.,karst cave,but also can detect the fracture zone or filling mode of karst cave,and at the same time,cannot use exploration holes or logging observation.The electromagnetic CT method can accurately detect the location and scale of the karst caves and has a higher accuracy detecting karst bands.In addition,exploration holes or well logging observations are also expected to be conducted,and their detection effect is greatly affected by lithology.

Site effect on strong-motion records of the 2011 Mw9.0 Tohoku earthquake in Japan

Strong-motion site effect was checked for four sites at comparable epicentral distances from the March 11, 2011 Mw9.0 Tohoku earthquake in Japan. The result showed that site condition had a significant impact on peak acceleration, and on maximal amplitude and characteristic period of its response spectrum. Shorter-period seismic waves were amplified mainly in shallower soils, while longer-period waves in deeper soft rocks and soils, where the characteristic periods of response spectra were longer than those on ground surface.

Baseline correction for near-fault ground motion recordings of the 2008 Wenchuan Ms8.0 earthquake

In this study,both records of a digital accelerometer and a seismograph at a far-field station for the 2008 Ms8.0 Wenchuan earthquake were analyzed,and a pulsive noise model for acceleration record was found.By comparing with the result of a rotary-table tilt test,we concluded that the noises in the acceleration records were caused by ground tilt as a result of rotational ground motion.We analyzed the key noises that may cause baseline offset,and proposed a baseline-correction scheme for preserving the long-period ground motion in accordance with specific pulse positions.We then applied this correction method to some near-field strong-motion acceleration records.The result shows that this method can obtain near-field ground displacements,including permanent displacements,in agreement with GPS data,and that this method is more stable than other methods.

Tectonic characteristics and structural styles of a continental rifted basin:Revelation from deep seismic reflection profiles

The Fushan Depression is a half-graben rifted sub-basin located in the southeast of the Beibuwan Basin, South China Sea. The Paleogene Liushagang sequence is the main hydrocarbon-bearing stratigraphic unit in the sub-basin. Using three-dimensional(3-D)seismic data and logging data over the sub-basin, we analyzed structural styles and sedimentary characteristics of the Liushagang sequence. Five types of structural styles were defined: ancient horst, traditional slope, flexure slope-break, faulted slope-break and multiple-stage faults slope, and interpretations for positions, background and development formations of each structural style were discussed. Structural framework across the sub-basin reveals that the most remarkable tectonic setting is represented by the central transfer zone(CTZ) which divides the sub-basin into two independent depressions, and two kinds of sequence architectures are summarized:(i) the western multi-stage faults slope;(ii) the eastern flexure slope break belt. Combined with regional stress field of the Fushan Depression, we got plane combinations of the faults, and finally built up plan distribution maps of structural system for main sequence. Also, we discussed the controlling factors mainly focused on subsidence history and background tectonic activities such as volcanic activity and earthquakes. The analysis of structural styles and tectonic evolution provides strong theoretical support for future prospecting in the Fushan subbasin and other similar rifted basins of the Beibuwan Basin in South China Sea.

Development of piezoelectric-based technology for application in civil structural health monitoring

Piezoelectric material,as one of the great potential materials,had attracted lots of attention all over the world due to its distinguish advantages.In this paper,the development of piezoelectric-based technology for application in the field of civil structural health monitoring(CSHM),was summarized and discussed.Based on the different identification mechanisms,the piezoelectric transducer-based technology can be divided into two main approaches as the active or passive sensing and detection methods.This paper summarized the development of these two approaches and discussed their applications in the area of civil structural health monitoring,such as structural and concrete engineering,bridge engineering,pipeline engineering,protection engineering for geological hazards and earthquake disasters,and so on.In addition,the electrical mechanical impedance(EMI)technique,as one of the active identification methods,was also detailly presented.Finally,its great potential for the piezoelectric-based technique was presented based on the detail discussion,especially in the areas of civil structural health monitoring.

New Study of Anshunsaurus huangnihensis Cheng,2007(Reptilia:Thalattosauria):Revealing its Transitional Position in Askeptosauridae

Anshunsaurus huangnihensis Cheng 的颅骨， 2007，特别颅骨房顶，在这份报纸详细被描述。比作 Askeptosauroidea 的另外的类和种， Anshunsaurus huangnihensis 从 Askeptosaurus italicus 有一些重要过渡人物到 Anshunsaurus huangguoshuensis：与在 Askeptosaurus italicus 和 Anshunsaurus huangguoshuensis 之间的颅骨长度有关的喙的长度；存在的 postfrontal 但是清楚地减少了；相关地短的 posterolateral 过程并且重叠顶骨。种系发生的分析微弱地从 Anshunsaurus huangnihensis 支持进化进步到 Anshunsaurus huangguoshuensis。骨胳的比率显示了在 Askeptosauridae 内集团之中的节点。Askeptosauridae 的进化方向应该从 Askeptosaurus italicus 到 Anshunsaurus huangguoshuensis。骨胳的比率显示进化进步是 Askeptosaurus italicus Anshunsaurus huangnihensis Anshunsaurus huangguoshuensis。在生物地理学省，从华南的 Askeptosauroidea taxa 从西方的 Tethys 与那些有一种靠近的关系；然而， Xinpusaurus 从晚三叠纪是与从东方太平洋的那些有关的更多。

Baseline correction for digital strong-motion records by using the pre-event portion

Baseline offset in digital strong-motion acceleration record and initial velocity can produce unrealistic results for ground velocity and displacement derived from the acceleration by integration.A new method is proposed for the baseline correction and initial velocity calculation.It is based on linear least-squares fitting of the pre-event portion of velocity derived from the uncorrected acceleration data.Compared with the conventional method,which is based on removing the mean values of the pre-event portions of the acceleration and velocity traces,this method has clearer physical meaning and better stability.

Damping modification factors for acceleration response spectra

DMF(Damping modification factors) are used to modify elastic response spectral values corresponding to damping ratio 5% to other damping levels. The influence of seismological parameters(magnitude,epicentral distances and site conditions) on DMF for acceleration spectra was analysed. The results show that for a given period as the magnitude or distance increase, the effect of damping on the seismic response will also increase, which indicates the response reduction from the structural damping will become more efficient. In the near-field of small earthquakes, the influence of site conditions on DMF is obvious, but it does not show a consistent rule. Furthermore, the DMF corresponding to different site conditions gradually close to unity with increasing magnitude and distance. The influence of the above mentioned parameters is related to the relative attenuation of the frequency components of the ground motion. The attenuation index alone is sufficient to take into account the influence. Based on these features, this paper proposes a formula of DMF for acceleration response spectra.

Depositional setting analysis using seismic sedimentology: Example from the Paleogene Lishagang sequence in the Fushan depression,South China Sea

The Fushan depression is a classic lacustrine rifted sub-basin in the Beibuwan Basin, South China Sea. The Paleogene Liushagang sequence is the main hydrocarbon-bearing stratigraphic unit in the depression.Using three-dimensional(3-D) seismic data and logging data, we analyzed depositional setting of the Liushagang sequence. We use wave impedance inversion to describe progradational directions of provenance and the general distribution of sand body. The seismic facies was analyzed by using the seismic sedimentology approach based on 3-D seismic data, and summed into eight types of seismic facies which could be well related to sedimentary facies. Seismic attributes with six objective sequence boundaries were extracted. Consequently, four provenance system of Liushagang sequence in the study area were confirmed by the corresponding relationship between the geologic information and the warm color and higher value area of seismic attributes:(i) the Hainan uplift provenance area in the south,(ii)the Linggao uplift provenance area in the west,(iii) the Yunlong uplift provenance area in the east and(iv) the northern provenance area. The seismic sedimentology used in this study may provide new insights into a better understanding of depositional setting in continental lacustrine rifted basins.

A New Eosauropterygian(Diapsida:Sauropterygia) from the Middle Triassic of Luoping,Yunnan Province

A new eosauropterygian,Largocephalosaurus polycarpon gen.et sp.nov.,was described based on a skeleton from the Middle Triassic of Luoping(罗平),Yunnan(云南) Province,southwestern China.The new taxon is characterized by a big skull,paired frontal,laterally expanded upper temporal fossa,anterior process of squamosal entering orbit,robust teeth with basally expanded crown and blunt tip,short cervical region,distinctly elongated transverse process of the dorsal vertebrae,short and broad dorsal ribs,stout gastralia,scapula with distinctly posterodorsally extending blade,distinctly robust humerus,eleven carpal ossifications,and a manual fomula of 2-3-4-5-5.A phylogenetic analysis suggests that Largocephalosaurus is the basal-most member of a clade including Wumengosaurus,Eu-ropean pachypleurosaurs,and Nothosauroidea.

Water presence detection in a concrete crack using smart aggregates

Liquid migrating into existing concrete cracks is a serious problem for the reliability of concrete structures and can sometimes induce full concrete structural failures.In this paper,the authors present recent research on water presence detection in concrete cracks using piezoceramic-based smart aggregate(SA)transducers.The active sensing approach,in which one piezoceramic transducer is used to generate stress waves and others are used to detect the stress wave responses,is adopted in this research.Cracks formed in concrete structures act as stress reliefs,which attenuate the energy of the signals received by the SAs.In case of a crack being filled with liquid,which changes the wave impedance,the piezoceramic transducers will report higher received energy levels.A wavelet packet-based approach is developed to provide calculated energy values of the received signal.These different values can help detect the liquid presence in a concrete crack.A concrete beam specimen with three embedded SAs was fabricated and tested.Experimental results verified that the SA-based active sensing approach can detect a concrete crack and further detect the liquid presence in the concrete crack.