Lateral Displacement Measurements Research Articles

Reliability testing of sonographic techniques in detecting lateral displacement of patellar tendon

ObjectivesPatellofemoral pain syndrome (PFPS), a common knee condition, is characterized as presence of peripatellar pain during activities especially during loading of the lower extremity. Gonzalez-Suarez et al. (2021) developed a sonographic technique that assessed patellar tendon displacement within the trochlear groove. This study aims to determine the reliability of this sonographic technique. MethodsIntra-rater and inter-rater reliability study of three sonologist on the lateral displacement of the patellar tendon using ultrasound. Patellar tendon displacement was assessed using the three novel sonographic measurement techniques: 1) region of trochlear groove where the patellar tendon midpoint is located, 2) distance between deepest portion of the trochlear groove and patellar tendon midpoint and 3) percentage of lateral displacement of the patellar tendon. The measurements were done with the patients in supine and standing. ResultsTen participants with a mean age of 27.6 ± 1.56 years were included in the study. Pilot studies were done to improve the sonographic technique. Intraclass correlation coefficients yielded good to excellent inter-rater and excellent intra-rater reliability (>0.75) in the supine and standing positions except the inter-rater reliability of the region of the trochlear groove where patellar tendon midpoint is in supine position. ConclusionThe sonographic techniques for measurement of lateral patellar tendon displacement showed good to excellent intra-rater and inter-rater reliability between sonologists of different levels of expertise using a well-defined scanning protocol.

Patellar articular overlap is better associated with patellar alignment during weight-bearing than traditional measures of patellar height

BackgroundA consequence of a high riding patella is reduced osseous stability and malalignment of the patella (i.e., lateral patellar tilt and displacement). Although quantification of patellar height is a routine part of the radiographic examination of the patellofemoral joint, it is not clear which measure of patellar height is best associated with patella alignment. Hypothesis/PurposeTo determine if patellar articular overlap (PAO) is better associated with lateral patellar tilt and lateral patellar displacement compared to traditional measures of patellar height. Study Design: Cross-sectional. MethodsMagnetic resonance images were obtained from 50 female participants (21 with patellofemoral pain and 29 healthy controls) under loaded conditions (25–35% bodyweight) at 15–20 degrees of knee flexion. Measurements of lateral patellar tilt and displacement as well as the PAO, Insall-Salvati ratio (ISV), Caton Deschamps-index (CD-index), or the Blacburn Peel-index (BP-index) were obtained from sagittal and axial plane images. ResultsThe PAO was found to significantly correlated with lateral patellar tilt (r = −0.77, p < 0.001). In contrast, the ISV, CD-index, or the BP-index were not found to be associated with lateral patellar tilt (r = 0.13, p = 0.34; r = −0.14, p = 0.33; r = −0.08, p = 0.56, respectively). Both the PAO and ISV were found to be significantly correlated with lateral patellar displacement (r = −0.52, p < 0.001; r = 0.43, p = 0.002, respectively). Conversely, the CD-index and BP-index were not found to be associated with lateral patellar displacement (r = 0.03 p = 0.83; r = 0.05 p = 0.74, respectively). ConclusionOf the measures of patellar height evaluated, the PAO was found to provide the greatest association with lateral patellar tilt and displacement.

Visual measurement of lateral relative displacement of wheel-rail of high-speed train under earthquake

When an earthquake causes the wheel-rail detachment of a high-speed train, the derailment evaluation criteria based on wheel-rail force faces failure. At this time, the lateral relative displacement of the wheel-rail (LRDWR) is more intuitive and continuous to assess the running safety of a high-speed train. In the past, many experimental studies have been conducted on measuring the LRDWR of trains. However, there is still a lack of effective measurement methods to solve the problem of LRDWR measurement in complex texture and high-speed dynamic scenes. Therefore, a lateral relative wheel-rail displacement measurement method based on machine vision and the improved Hourglass network (LRWRDVH) is proposed in this paper to determine the LRDWR by predicting the pixel coordinates of a few wheel-rail keypoints. The scaled-down bridge running test of the high-speed train is designed for validation, and then the LRDWR measurement of high-speed train under earthquake is carried out using the LRWRDVH method to evaluate the running safety of high-speed train. The test results show that the LRWRDVH method is effective and accurate and can be further used to study the running safety of high-speed trains under earthquakes.

Ultrasensitive label-free miRNA-21 detection based on MXene-enhanced plasmonic lateral displacement measurement

Abstract miRNAs are small non-coding RNA molecules which serve as promising biomarkers due to their important roles in the development and progression of various cancer types. The detection of miRNAs is of vital importance to the early-stage diagnostics and prognostics of multiple diseases. However, traditional detection strategies have faced some challenges owing to the intrinsic characteristics of miRNAs including small size, short sequence length, low concentration level and high sequence homology in complex real samples. To overcome these challenges, we proposed a MXene-enhanced plasmonic biosensor for real-time and label-free detection of miRNA. By utilizing MXene nanomaterial which possesses unique characteristics including large surface area and strong carrier confinement abilities, we tuned the absorption of our plasmonic sensing substrate to reach a “zero-reflection” state and induced an extremely sharp phase change at the resonance angle. Combined with the sensing mechanism based on phase-induced lateral displacement measurement, this MXene-enhanced plasmonic biosensor can achieve a much superior sensing performance compared to traditional SPR devices. Based on this biosensing scheme, the ultrasensitive detection of target miRNA with a detection limit down to 10 fM has been successfully demonstrated. More importantly, single-base mismatched miRNA can be easily distinguished from the target miRNA according to the sensing signal. Furthermore, our plasmonic biosensor is capable of detecting miRNA in complex media such as 100 % human serum samples without compromising the detection sensitivity. This MXene-enhanced plasmonic sensing scheme has the ability of detecting miRNAs with extremely low concentration levels in complex surrounding media without the need of introducing extra labels or amplification tags, which holds great potential in various biological applications and clinical diagnostics.

High-precision laser beam lateral displacement measurement based on differential wavefront sensing.

Accurately lateral displacement measurement is essential for a vast of non-contact sensing technologies. Here, we introduce a high-precision lateral displacement measurement method based on differential wavefront sensing (DWS). Compared to the conventional differential power sensing (DPS) method, the DWS method based on phase readout has the potential to achieve a higher resolution. The beam lateral displacement can be obtained by the curvature distribution of the wavefront on the surface of the detector. According to the theoretical model of the DWS method, the sensitivity of the lateral displacement can be greatly improved by increasing the wavefront curvature of the measured laser beam by means of lenses. An optical system for measuring the lateral displacement of the laser beam is built and calibrated by a high-precision hexapod. The experimental results show that the DWS-based lateral displacement measurement achieves a resolution of 40 pm/Hz1/2 (at 1-10 Hz) with a linear range of about 40 µm, which is consistent with the theoretical model. This technique can be applied to high-precision multi-degree-of-freedom interferometers.

Ultrasound Measurement of Lateral Patellar Displacement: A Cadaveric Validation Study.

BackgroundPatellofemoral pain syndrome (PFPS) is one of the most common musculoskeletal complaints seen in outpatient settings. It has been suggested that hip adduction creates loads on the iliotibial band and causes lateral displacement of the patella (patellar tilt), which can lead to uneven patellofemoral joint loading, and hence, cause patellofemoral pain. In previous studies in the literature, ultrasound has been used to measure lateral patellar displacement. However, the method lacks validity data.Purpose/HypothesisThe aim of this study was to validate the use of ultrasound to measure lateral displacement of the patella, by comparing the position of the patella as measured first by ultrasound, and then by direct measurement.Study DesignDescriptive Laboratory Study.MethodsNine soft-fixed cadavers were used in this study. The cadavers had been donated for anatomical examination and research under the Human Tissue Act (2004). The distance between the lateral femoral condyle and the lateral edge of the patella were measured by B-mode real-time ultrasound, and then by direct measurement, in two positions, neutral and at 20° hip adduction.ResultsThe mean difference in the patella-to-lateral femoral condyle distance in the neutral position and at 20° adduction was 0.27 cm (ultrasound), and 0.34 cm (direct measurement), respectively. There were no significant differences between the measurements obtained by US and by direct measurement (Pearson correlation= 0.97, p=0.83).ConclusionUltrasound is a valid and reliable method for measuring patellar position relative to the femoral condyle, and the validity data reported here suggest that it can be used with confidence in clinic to assess lateral patellar displacement.Level of Evidence3

Measuring Deltoid Insufficiency after Supination-External Rotation Ankle Fracture with Lateral Talar Subluxation on Gravity Stress View

Category: Trauma; Ankle Introduction/Purpose: Supination-external rotation (SER) variant ankle fracture is common, and identifying the unstable SER variants requiring surgery has been controversial. Stress view radiographs are frequently obtained to assist in decision-making. Measurement of the medial clear space (MCS) is used to determine medial structure integrity. SER variant ankle injuries are characterized by talus external rotation, and posterolateral translation causing a posterior displaced distal fibula fracture, with possible medial and posterior injury at further subluxation events. We propose that the MCS measurement is flawed by measuring from the point of rotational pivoting. Measurement of lateral displacement of the lateral talus versus the tibial plafond will be a more sensitive measurement tool for an injury mechanism characterized by external rotation and posterolateral subluxation. Methods: IRB-approved, retrospective review of ankle injury radiographs for acute SER-variant isolated lateral malleolar fractures during a 3-year consecutive period. Patients were included if they had a gravity-stress view (GSV) evaluation. Patients were excluded for different fracture morphology, pediatric fractures, no GSV films, or prior history of ankle or foot arthritis or trauma. A priori power analysis was performed demonstrating 32 patients would be required to detect a change in 2mm. 102 patients underwent analysis. GSV were analyzed with measurements taken of the medial clear space (MCS), superior clear space (SCS), and we propose two novel measurements of lateral talus subluxation (LTS) by comparison to the anterior ankle syndesmosis marked by a vertical line at the tibial plafond. Standardized measurements were acquired by foot-and-ankle fellowship-trained orthopaedic surgeons and musculoskeletal radiologists. ICC data was obtained. Surgeons separately provided blinded decisions- for-surgery which patients appeared to have ankle instability requiring surgical stabilization. Results: Measurements were performed for 102 patients, there were no significant differences in baseline demographics. There was a statistically significant increase in mean MCS, SCS, and LTS within the operative group (MCS 7.3 vs 5, p=0.005, SCS 4.6 vs 3.9, p=0.02, LTS 6.1 vs 2.9, p &lt;0.001) with the LTS having the highest statistical significance. Pearson correlation analysis demonstrated positive and significant correlations between MCS and SCS (0.43, 0.37, P&lt;0.001), MCS and LTS (0.51, p&lt;0.001). MCS &gt;=5mm had a sensitivity of 95% and specificity of 60% in our cohort, LTS &gt;4mm demonstrating the same sensitivity (95%) with improved specificity to 75%. Receiver-operator-characteristic analysis for MCS vs LTS demonstrates an area under the curve (AUC) 0.786 for MCS &gt;4 versus LTS (AUC) 0.918. Conclusion: The LTS measurement is superior to MCS measurement as a surrogate for medial ankle structure stability. We propose that ankle joint subluxation can be more accurately identified by measuring nearer to the point of maximal talar displacement in an external rotation and posterolaterally displacing injury pattern. The LTS measurement elevation &gt;4mm was found to be superior to the MCS measurement &gt;4mm in all categories, with high sensitivity and specificity, and superior performance in ROC analysis. We propose this will be a useful tool for clinicians when evaluating SER variant ankle fractures.

Assessment of lateral and vertical tissue displacement obtained by the retraction cord and diode laser

This study was carried out to compare between two techniques of gingival retraction (retraction cord and diode laser) regarding the amount of tissue displacement both laterally and vertically. Also, Patient satisfaction during their application. Methodology: twenty two cases requiring full coverage porcelain fused to metal fixed prosthesis in the anterior esthetic zone were taken from the outpatient clinic of the fixed prosthodontics department – Cairo University. The teeth were prepared with subgingival deep chamfer finish line and were distributed according to the technique of gingival retraction. Group I: Patients receiving retraction with the retraction cord. Group II: Patients receiving retraction with diode laser. In both groups measurement of lateral and vertical displacement done by using the stereomicroscope. also, patient satisfaction was measured by Comley and Demeyer numeric pain scale. There was significant difference between the two groups regarding lateral and vertical displacement. Laser troughing give not only more amount of vertical but also more lateral retraction whereas, P&lt;0.05. For the patient satisfaction there was a significant difference between both groups, with laser troughing give better results.

Study on Measurement of Lateral Displacement for Vehicles Traveling on Road with Electromagnetic Guidance

Study on Measurement of Lateral Displacement for Vehicles Traveling on Road with Electromagnetic Guidance

Evaluation of Lateral and Axial Deformation for Earth Pressure Balance (EPB) Tunnel Construction Using 3 Dimension Finite Element Method

Mass Rapid Transit Jakarta (MRTJ) phase 1 tunnel construction using the earth pressure balance method has been completed and surface settlement and lateral displacement data according to elevation and inclinometer readings has been collected to evaluate the effect of tunnel’s construction on surrounding infrastructure. Soil stratification along the research area, defined according to boring logs and soil parameters for the hardening soil model (HSM) and the soft soil model (SSM), was determined by optimization of stress-strain curve fitting between CU triaxial test, consolidation test and soil test models in the Plaxis 3D software. Evaluation of the result of surface settlement measurements using an automatic digital level combined with geodetic GPS for elevation and position control points showed that the displacement behavior was affected by vehicle load and stiffness of the pavement. Lateral displacement measurements using inclinometers give a more accurate result since they are placed on the soil and external influences are smaller than surface settlement measurement. The result of 3D finite element modeling showed that surface settlement and lateral displacement during TBM construction can be predicted using HSM with 2% contraction. SSM and the closed-form solutions of Loganathan and Poulos are unable to provide a good result compared to the actual displacement from measurements.

Coseismic Surface Displacement in the 2019 Ridgecrest Earthquakes: Comparison of Field Measurements and Optical Image Correlation Results

AbstractA fundamental topic in earthquake studies is understanding the extent to which fault rupture at the surface is localized on primary fault strands as opposed to distributed tens to hundreds of meters away from primary ruptures through off‐fault deformation (OFD) via a combination of discrete secondary faulting and bulk deformation. The 2019 Ridgecrest, CA Mw6.4 and Mw7.1 earthquakes provide an opportunity to explore this problem via comparison of published field‐based and mostly on‐fault offset measurements, with new lateral displacement measurements made over length scales of hundreds of meters across the primary rupture using WorldView satellite images collected before and after the earthquakes. A mean fit to the field observations underestimates net slip (pixel‐correlation results) by an average of 0.4 m along the Mw6.4 rupture (∼41% of net left‐lateral displacement) and 0.7 m along the Mw7.1 rupture (∼65% of net right‐lateral displacement). We attribute these differences to substantial OFD along the lengths of the Mw6.4 (∼59%) and Mw7.1 (∼35%) ruptures. A maximum fit to the field observations provides an improved match to the pixel correlation results (difference of 0.1–0.2 m or ∼76%–98% of net displacement). OFD may in part depend on displacement magnitude, where locations along the rupture with smaller displacements (&lt;2 m) are characterized by a greater percentage of OFD. Furthermore, OFD increases with rupture zone width, especially at the scale of individual rupture strands (hundreds of meters). These findings contribute to a growing understanding of the important role of OFD in accommodating deformation near the surface.

Lateral Displacement Measurement Device for Concrete Specimens with Noncylindrical Cross Section

AbstractThe increasing need to calibrate and validate multiscale numerical models cries out for new experimental devices and methodologies. This paper presents an experimental measurement device of...

Measurement Reliability in Pediatric Lateral Condyle Fractures of the Humerus.

Lateral condyle fractures of the distal humerus are the second most common pediatric elbow fracture. A difference of 1 or 2 mm in fracture displacement measurement may change the operative or nonoperative management of a minimally displaced fracture. The goal of this study was to determine the interobserver and intraobserver agreement in the measurements of displacement of lateral condyle fractures of the humerus. A retrospective radiographic review of 60 patients was performed by 3 reviewers. Fracture displacement was measured in millimeters on all radiographic projections and repeated by a single author 1 month later. Intraclass correlation coefficients (ICC) were calculated for intraobserver and interobserver agreement. We then calculated the percentage of measurements that differed by >1 or 2 mm. Analysis was performed on the entire cohort of displaced fractures and again separately for a cohort of minimally displaced fractures (defined as <5 mm). The combined ICC for intraobserver reliability across all radiographic projections was 0.96 (range, 0.952 to 0.977), but there was disagreement between a single reviewer's own measurements 17.3% of the time. Within the cohort of fractures displaced <5 mL, this intrarater disagreement (>2 mm) dropped to 4%. Interobserver reliability was also high with an ICC of 0.90 (range, 0.861 to 0.924). Within the minimally displaced cohort (<5 mm), the interrater disagreement was 6.6% when using a 2 mm cutoff and 22.2% when using a 1 mm cutoff. Intraobserver and interobserver reliability are high when measuring lateral condyle fractures and the percent of clinical disagreement is low when measuring minimally displaced fractures for which treatment depends on measuring to the millimeter. The internal oblique projection is the most reliable view for measuring lateral condyle fracture displacement, whereas the external oblique view offers little in terms of reliability. This study may be used as a platform for further research, verifying that reliable measurements of lateral humeral condyle fracture displacement can be obtained within 1 to 2 mm from adequate plain films. Level III.

Single Chip-Based Nano-Optomechanical Accelerometer Based on Subwavelength Grating Pair and Rotated Serpentine Springs.

Optical coupling between subwavelength grating pairs allows for the precise measurement of lateral or vertical displacement of grating elements and gives rise to different types of displacement and inertial sensors. In this paper, we demonstrate a design for a nano-optomechanical accelerometer based on a subwavelength grating pair that can be easily fabricated by a single Silicon-on-insulator (SOI) chip. The parameters of the subwavelength grating pair-based optical readout, including period, duty cycle, thickness of grating and metal film, and the distance of the air gap, were optimized by combining a genetic algorithm and rigorous coupled wavelength analysis (RCWA) to obtain the optimal sensitivity to the displacement of suspended grating element and the acceleration. A corresponding mechanical design was also completed to meet the highly sensitive acceleration measurement requirement while considering the mechanical cross-axis sensitivity, dynamic range, bandwidth, and fabrication feasibility. This device was verified by both RCWA and finite-different-time-domain methods, and a tolerance analysis was also completed to confirm that it is able to achieve the extremely high optical displacement sensitivity of 1.8%/nm, acceleration-displacement sensitivity of 1.56 nm/mg, and acceleration measurement sensitivity of more than 2.5%/mg, which is almost one order of magnitude higher than any reported counterparts. This work enables a single SOI-based high performance accelerometer, and provides a theoretical basis and fabrication guides for the design.

Dynamic Fiber-Optic Shape Sensing Using Fiber Segment Interferometry

Dynamic fiber-optic shape sensing, often also referred to as curvature or bend sensing, is demonstrated using fiber segment interferometry, where chains of fiber segments, separated by broadband Bragg grating reflectors, are interrogated using range-resolved interferometry. In this paper, the theory of interferometric curvature sensing using fiber segments is developed in detail, including techniques to infer lateral displacements from the measured differential strain data and methods for directional calibration of the sensor. A proof-of-concept experiment is performed, where four fiber strings, each containing four fiber segments of gauge length 20 cm each, are attached to the opposing sides of a flexible support structure and the resulting differential strain measurements are used to determine the lateral displacements of a 0.8 m cantilever test object in two dimensions. Dynamic tip displacement measurements at $ \mathbf{40}\;\mathbf{nm}\cdot \mathbf{Hz}^{-0.5}$ noise levels over a 21 kHz bandwidth demonstrate the suitability of this approach for highly sensitive and cost-effective fiber-optic lateral displacement or vibration measurements.

Analysis of the parameters affecting the mechanical behaviour of straw bales under compression

Straw bale construction is a building technique that has excellent thermal performance and limited impact on the environment. Improving knowledge of the mechanical properties of straw bales is important to understand the behaviour of straw bale buildings, especially in case of natural calamities, where straw bales may carry mechanical load and act as a “surviving cell”. The results of extensive tests conducted on bales of different materials are presented. The influence of the material, bale density, bale orientation, baling process and loading rate on the mechanical properties of straw bales was investigated. Force-displacement curves obtained from monotonic compression tests were analysed and relationships between the mechanical properties of straw bales and their geometry and density were determined. Continuous measurements of bales lateral displacement allowed Poisson's ratio to be calculated and, using a simple model, the strain to which bale strings are subjected during loading was estimated. Young's modulus was shown to mainly depend on the square of the density, while no influence of the loading rate and of strings pre-tension was observed. The Poisson's ratio did not remain constant during loading and it exhibited a different trend depending on the orientation of the bales. Moreover, it was observed that for flat bales a rearrangement of the straw fibres during loading occured and the maximum strings strain remained limited. Strings strain reached higher values for on-edge bales instead, and strings bursts occured more frequently.

Investigation of displacement measurement method based on fringing field capacitor

Capacitive fringing field sensors have been used in some non-contact detections. A lateral displacement measurement method based on fringing field capacitors is investigated by simulations and experiments in this study. For the conventional interdigitated structure, the periodic electric field distribution is obtained because of those alternate electrodes, which produces periodic capacitances along with the target displacement. However, it is inconvenient to construct measurement systems due to the non-linear capacitance output. A dentate structure is proposed to improve the output characteristics of displacement measurement. The periodic uniform electric field is achieved by the dentate electrodes, which brings the linear capacitance variation in every period. Indium–tin oxide film was employed to fabricate a prototype, and the experiment results indicate that the dentate structure can be used in the lateral displacement measurement for its linear output characteristics.

An Optical Fiber Lateral Displacement Measurement Method and Experiments Based on Reflective Grating Panel.

An optical fiber sensing method based on a reflective grating panel is demonstrated for lateral displacement measurement. The reflective panel is a homemade grating with a periodic variation of its refractive index, which is used to modulate the reflected light intensity. The system structure and operation principle are illustrated in detail. The intensity calculation and simulation of the optical path are carried out to theoretically analyze the measurement performance. A distinctive fiber optic grating ruler with a special fiber optic measuring probe and reflective grating panel is set up. Experiments with different grating pitches are conducted, and long-distance measurements are executed to accomplish the functions of counting optical signals, subdivision, and discerning direction. Experimental results show that the proposed measurement method can be used to detect lateral displacement, especially for applications in working environments with high temperatures.

Three-Dimensional Oscillation Dynamics of the In Situ Piston Rod Transmission Between Buoy Line and the Double Hinge-Connected Translator in an Offshore Linear Wave Energy Converter

Force and displacement measurements have been performed in situ on the piston rod mechanical lead-through transmission in the direct drive of the second experimental wave energy converter (WEC) 3 km offshore at the Lysekil research site (LRS) during a 130-day continuous full-scale experiment in 2009. The direct drive consists of a buoy line and a piston rod transmission with a double-hinged link (DHL) at the lower end connecting the point absorbing surface-floating buoy to the translator of an encapsulated permanent magnet linear generator on the seabed. The buoy line is guided by a funnel in the buoy line guiding system 3.2 m above the generator capsule. The 3 m long piston rod reciprocates through a mechanical lead-through in the capsule wall, sealing off seawater from entering the generator capsule. A setup of laser triangulation sensors measures the relative lateral displacement of the piston rod. This paper introduces a method and a system of equations for calculating piston rod relative tilt angle and piston rod azimuth direction of tilting from the relative lateral displacement measurements. Correlation with piston rod axial displacement and forces enables evaluation of the three-dimensional (3D) oscillation dynamics. Results are presented from 2 weeks after launch and from 3 months after launch in altogether four cases representing two different stages of wear in two different sea states. Piston rod tilting from accumulated wear in the buoy line guiding system is separated from tilting due to elastic displacement. Structural mechanical finite element method (FEM) simulations verify the magnitude of elastic displacement and indicate negligible stress and strain at the mounting point of the laser sensor setup. The proposed theory for piston rod 3D motion is validated by the experiment. As the experiment progressed, wear in the buoy line guiding system accelerated due to splitting of the buoy line jacketing compound, thereby increasing the piston rod tilt angles. Over 94 days into the experiment, 21.8 mm of accumulated wear in the buoy line guiding system had altered the characteristics of the piston rod oscillations and increased the maximum piston rod relative tilt angle by 0.39 deg in the predominant azimuth direction of wave propagation. Further accumulated wear in the buoy line guiding system led to buoy line rupture 130 days after launch. The results presented in this paper have been used in assessments for improving the mechanical subsystems in subsequent experimental WECs based on the Uppsala concept.

Ground Response to Multiple Parallel Microtunneling Operations in Cemented Silty Clay and Sand

AbstractThis paper presents a case history of the successful application of observational method to instruction microtunneling with successive pipe-jacking. The microtunneling project is the construction of four parallel pipes under Guan River in Jiangsu, China. Four parallel tunnels with external diameter of 4,160 mm and horizontally spaced at 4.8 m apart were jacked over 450 m in cemented silty clay and sand by two slurry-balance microtunnel boring machines (MTBM) at a depth of 4.6 m under the river bed. Since the overburden soil is very thin, proper control of tunneling operations was of utmost importance for maintaining the stability of the river bed. In order to optimize the operation parameters prior to construction under the river bed, a field trial was conducted, which included measurement of ground surface settlement, subsurface settlement, and lateral displacement of the subsurface soils, as well as excess pore water pressure and earth pressure. The relationship between ground response and const...