Lateral cyclic response of an aluminum model pile in sand     

Jiunn-Shyang Chiou  Zhi-Wei Xu  Cheng-Chang Tsai  Jin-Hung Hwang 《Marine Georesources & Geotechnology》2018,36(5):554-563

Lateral cyclic load tests were performed on an aluminum model pile in dry sand. Two levels of loading were adopted to represent different service load conditions. The maximum number of loading cycles was 1,000. From the test results, it was found that the even though in the service load condition, the pile response was still affected by cyclic effects and a larger load level would produce more significant influence. In a global point of view, the lateral displacement and maximum moment increased with loading cycles, while the secant stiffness within a cycle decreased with cycles. The cyclic effect was more significant on the lateral displacement than on the moment. In a local point of view, cyclic loading would degrade the equivalent subgrade stiffness for the soil shallower than about seven times diameter. In addition, the secant subgrade stiffness within a cycle increased with loading cycles. Some experimental relationships of lateral pile response and loading cycles were built and compared with those in the literature.  相似文献   

Aquifer Characterization Using Fiber Bragg Grating Multi-Level Monitoring System     

Yu-Li Wang  Liang-Cheng Chang  Fei Liu  Yen-Te Ho  Tzu Bin Wang  Tian-Chyi Jim Yeh  Jui-Pin Tsai 《Ground water》2022,60(4):518-529

Groundwater responses measured from multiple wells at different depths are essential for delineating the aquifer heterogeneity using hydraulic tomography (HT). In general, conducting HT requires many wells because traditional well monitoring is usually partially open at a specific depth interval or is fully penetrating. Accordingly, conducting an HT survey is typically costly and time-consuming. To tackle these issues, a new multi-level monitoring system (MLMS) for the HT survey was developed using the fiber Bragg grating (FBG) technique. This FBG MLMS could collect the depth-discrete groundwater observations from a fully penetrated 2-inch well. Three field campaigns were conducted to validate the capability of the FBG MLMS for HT surveys. The results show that the accuracy and stability of this MLMS are reliable and that FBG MLMS is beneficial for conducting an HT survey. Specifically, compared to the traditional monitoring well in an injection event, this FBG MLMS can concurrently cause an increase in the number of cross-hole tests several times and collect many more head observations than the standard methods, resulting in the observed flow fields efficiently reaching ergodic conditions and effectively improving the accuracy of the estimated hydraulic heterogeneity. Therefore, the FBG MLMS could be an alternative MLMS for efficiently and economically conducting an HT survey.  相似文献   

New P–T constraints on the Tamayen glaucophane‐bearing rocks,eastern Taiwan: Perple_X modelling results and geodynamic implications          下载免费PDF全文

I. Baziotis  C.‐H. Tsai  W. G. Ernst  B.‐M. Jahn  Y. Iizuka 《Journal of Metamorphic Geology》2017,35(1):35-54

New pseudosection modelling was applied to better constrain the P–T conditions and evolution of glaucophane‐bearing rocks in the Tamayen block of the Yuli belt, recognized as the world's youngest known blueschist complex. Based on the predominant clinoamphibole, textural relationships, and mineral compositions, these glaucophane‐bearing high‐P rocks can be divided into four types. We focused on the three containing garnet. The chief phase assemblages are (in decreasing mode): amphibole + quartz + epidote + garnet + chlorite + rutile/titanite (Type‐I), phengite + amphibole + quartz + garnet + chlorite + epidote + titanite + biotite + magnetite (Type‐II), and amphibole + quartz + albite + epidote + garnet + rutile + hematite + titanite (Type‐III). Amphibole exhibits compositional zoning from core to rim as follows: glaucophane → pargasitic amphibole → actinolite (Type‐I), barroisite → Mg‐katophorite/taramite → Fe‐glaucophane (Type‐II), glaucophane → winchite (Type‐III). Using petrographic data, mineral compositions and Perple_X modelling (pseudosections and superimposed isopleths), peak P–T conditions were determined as 13 ± 1 kbar and 550 ± 40 °C for Type‐I, 10.5 ± 0.5 kbar and 560 ± 30 °C for Type‐II (thermal peak) and 11 ± 1 kbar and 530 ± 30 °C for Type‐III. The calculations yield higher pressures and temperatures than previously thought; the difference is ~1–6 kbar and 50–200 °C. The three rock types record similar P–T retrograde paths with clockwise trajectories; all rocks followed trajectories with substantial pressure decrease under near‐isothermal conditions (Type‐I and Type‐III), with the probable exception of Type‐II where decompression followed colder geotherms. The P–T paths suggest a tectonic environment in which the rocks were exhumed from maximum depths of ~45 km within a subduction channel along a relative cold geothermal gradient of ~11–14 °C km^?1.  相似文献   

Was the M<Subscript>w</Subscript> 7.5 1952 Kern County,California, earthquake induced (or triggered)?     

Susan E. Hough  Victor C. Tsai  Robert Walker  Fred Aminzadeh 《Journal of Seismology》2017,21(6):1613-1621

Several recent studies have presented evidence that significant induced earthquakes occurred in a number of oil-producing regions during the early and mid-twentieth century related to either production or wastewater injection. We consider whether the 21 July 1952 M_w 7.5 Kern County earthquake might have been induced by production in the Wheeler Ridge oil field. The mainshock, which was not preceded by any significant foreshocks, occurred 98 days after the initial production of oil in Eocene strata at depths reaching 3 km, within ~1 km of the White Wolf fault (WWF). Based on this spatial and temporal proximity, we explore a potential causal relationship between the earthquake and oil production. While production would have normally be expected to have reduced pore pressure, inhibiting failure on the WWF, we present an analytical model based on industry stratigraphic data and best estimates of parameters whereby an impermeable splay fault adjacent to the main WWF could plausibly have blocked direct pore pressure effects, allowing the poroelastic stress change associated with production to destabilize the WWF, promoting initial failure. This proof-of-concept model can also account for the 98-day delay between the onset of production and the earthquake. While the earthquake clearly released stored tectonic stress, any initial perturbation on or near a major fault system can trigger a larger rupture. Our proposed mechanism provides an explanation for why significant earthquakes are not commonly induced by production in proximity to major faults.  相似文献   

Seismic fracture evaluation of diaphragm joints in welded beam-to-box column moment connections     

Ching-Yi Tsai  Keh-Chyuan Tsai  Chao-Hsien Li  Chung-Che Wu  Ker-Chun Lin  Sheng-Jhih Jhuang 《地震工程与结构动力学》2020,49(13):1344-1362

Steel box columns are widely used in steel building structures in Taiwan due to their dual strong axes. To transfer the beam-end moment to the column, diaphragm plates of the same thickness and elevations as the beam flanges are usually welded inside the box column. The electro-slag welding (ESW) process is widely used to connect the diaphragms to the column flanges in Taiwan because of its convenience and efficiency. However, ESW may increase the hardness of the welds and heat-affected zones (HAZs), while reducing the Charpy-V notch strength in the HAZ. This situation can cause premature fracture of the diaphragm-to-column flange welds before a large plastic rotation is developed in the beam-to-box column joints. To quantify the critical eccentricity and the effectiveness of fracture prediction, this study uses fracture prediction models and finite element model (FEM) analysis to correlate the test results. In this study, two beam-to-box column connection subassembly tests are conducted with different loading protocols and ESW chamber shapes. To implement a fracture prediction model, the material parameters are established from circumferential notched tensile tests and FEM analysis. Test results indicate that the fracture instances can be predicted on the basis of the cumulative plastic deformation in the HAZs. Analytical results indicate that fracture instances and locations are sensitive to the relative locations of the ESW joints and beam flange. Tests also confirm that the possible fracture of the diaphragm-to-column flange joints can be mitigated by enlarging the chamber of the ESW joint.  相似文献   

Including spatial distribution in a data‐driven rainfall‐runoff model to improve reservoir inflow forecasting in Taiwan          下载免费PDF全文

Meng‐Jung Tsai  Robert J. Abrahart  Nick J. Mount  Fi‐John Chang 《水文研究》2014,28(3):1055-1070

Multi‐step ahead inflow forecasting has a critical role to play in reservoir operation and management in Taiwan during typhoons as statutory legislation requires a minimum of 3‐h warning to be issued before any reservoir releases are made. However, the complex spatial and temporal heterogeneity of typhoon rainfall, coupled with a remote and mountainous physiographic context, makes the development of real‐time rainfall‐runoff models that can accurately predict reservoir inflow several hours ahead of time challenging. Consequently, there is an urgent, operational requirement for models that can enhance reservoir inflow prediction at forecast horizons of more than 3 h. In this paper, we develop a novel semi‐distributed, data‐driven, rainfall‐runoff model for the Shihmen catchment, north Taiwan. A suite of Adaptive Network‐based Fuzzy Inference System solutions is created using various combinations of autoregressive, spatially lumped radar and point‐based rain gauge predictors. Different levels of spatially aggregated radar‐derived rainfall data are used to generate 4, 8 and 12 sub‐catchment input drivers. In general, the semi‐distributed radar rainfall models outperform their less complex counterparts in predictions of reservoir inflow at lead times greater than 3 h. Performance is found to be optimal when spatial aggregation is restricted to four sub‐catchments, with up to 30% improvements in the performance over lumped and point‐based models being evident at 5‐h lead times. The potential benefits of applying semi‐distributed, data‐driven models in reservoir inflow modelling specifically, and hydrological modelling more generally, are thus demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

A physical model of the high-frequency seismic signal generated by debris flows     

Maxime Farin  Victor C. Tsai  Michael P. Lamb  Kate E. Allstadt 《地球表面变化过程与地形》2019,44(13):2529-2543

We propose a physical model for the high-frequency (>1 Hz) spectral distribution of seismic power generated by debris flows. The modeled debris flow is assumed to have four regions where the impact rate and impulses are controlled by different mechanisms: the flow body, a coarser-grained snout, a snout lip where particles fall from the snout on the bed, and a dilute front composed of saltating particles. We calculate the seismic power produced by this impact model in two end-member scenarios, a thin-flow and thick-flow limit, which assume that the ratio of grain sizes to flow thicknesses are either near unity or much less than unity. The thin-flow limit is more appropriate for boulder-rich flows that are most likely to generate large seismic signals. As a flow passes a seismic station, the rise phase of the seismic amplitude is generated primarily by the snout while the decay phase is generated first by the snout and then the main flow body. The lip and saltating front generate a negligible seismic signal. When ground properties are known, seismic power depends most strongly on both particle diameter and average flow speed cubed, and also depends on length and width of the flow. The effective particle diameter for producing seismic power is substantially higher than the median grain size and close to the 73rd percentile for a realistic grain size distribution. We discuss how the model can be used to estimate effective particle diameter and average flow speed from an integrated measure of seismic power. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.  相似文献   

Numerical study of upper ocean response to a typhoon moving zonally across the Luzon Strait   总被引：1，自引：0，他引：1  

Yi-Chun Kuo  Ching-Sheng Chern  Joe Wang  Ya-Ling Tsai 《Ocean Dynamics》2011,61(11):1783-1795

The Luzon Strait (LS) is a wide channel between Taiwan and the Luzon islands. Eastward of the LS, the Kuroshio Current (KC) flows northward along the eastern coasts of Luzon and Taiwan. A typhoon is a strong and localized low-pressure weather system that occurs frequently in the vicinity of the Taiwan area. One typical typhoon track, passing through the seas surrounding Taiwan, is a zonal path across the LS. The satellite measured SST, corresponding to typhoons Pabuk (5 Aug. 2007–12 Aug. 2007) and Dujuan (29 Aug. 2003–5 Sep. 2003), which both moved along this path, demonstrated that a classic right bias cooling occurs to the north of the storm track, during the typhoon forced period. However, some cold anomaly water also present toward left (south) of the storm track east of the LS in the relaxation period. This paper adopted a three-dimensional hydrostatic primitive equation model to study the possible causes of this southward transport of cold waters. Both model results and the observed SST anomaly revealed that the strength of the upper ocean cooling depends on whether a resonant regime between the typhoon winds and the near-inertial currents can be excited. To the east of the LS, the convergence between the warm Kuroshio water and the cold wakes in the poststorm period will enhance the southward spreading of cold anomaly water. The enhanced vertical mixing, induced by the southward propagation of nearly inertial waves associated with the cold wakes, can also produce some cold anomaly to the south of a storm track in the poststorm period. Both mechanisms can contribute to the occurrence of some cold anomaly water to the south of the storm track east of the KC. To the west of the LS, the convergence between the warm Kuroshio water and the cold upwelling water from the northern South China Sea can further strengthen the Kuroshio front in the LS.  相似文献   

Long-term (1998–2007) trends on the spatial distribution of heterotrophic ciliates in the East China Sea in summer: effect of the Three Gorges Dam construction     

An-Yi Tsai  Gwo-Ching Gong  Kuo-Ping Chiang  Chien-Fu Chao  Herng-Ru Guo 《Journal of Oceanography》2011,67(6):725-737

The spatial distribution of heterotrophic ciliates, environmental factors and potential food items (bacteria, Synechococcus spp. and nanoflagellates) were measured in the East China Sea to examine which variables contributed importantly to the long-term distribution of ciliates between 1998 and 2007. In July 1998 and June 2003, heterotrophic ciliates were found to be abundant (1,000–2,000 × 10³ cells m⁻³) in regions where surface salinity <32 but extremely low (<500 × 10³ cells m⁻³) in shelf waters of surface salinity >32. After August 2003, shortly after the completion of the Three Gorges Dam, we found no significant areal differences in the abundance of heterotrophic ciliates (HC). However, we found a significantly negative correlation between temperature and HC abundance of surface water after the completion of the dam, suggesting that temperature had a greater influence on HC abundance, once the original saline state had changed. For the long-term trends on the vertical distribution of HC, their abundance was significantly higher in the upper 50 m of the water column than at either 75 or 100 m. Abundance of Synechococcus spp. at these levels varied significantly in regions of surface salinity <32, suggesting that ciliates and picophytoplankton contribute greatly to mediating the transfer of organic matter to higher trophic levels in this marine ecosystem.  相似文献   

Dispersive thermohaline convection near salt domes: a case at Napoleonville Dome,southeast Louisiana,USA     

Zahra Jamshidzadeh  Frank T. -C. Tsai  Hasan Ghasemzadeh  Seyed Ahmad Mirbagheri  Majid Tavangari Barzi  Jeffrey S. Hanor 《Hydrogeology Journal》2015,23(5):983-998

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