Apparatus For Measuring Concrete Strength And Slip Form Method For Constructing Vertical Concrete Column Member Using Surface Wave Velocity Measurement Device

A slip form construction method of fabricating a vertical concrete column member by casting concrete while raising a sliding slip form, the slip form construction method comprising the steps of

• measuring a strength of concrete by a process of:
• installing an surface wave velocity measurement device, comprising an ultrasonic transmission probe configured to generate the ultrasonic waves within the concrete, a first contact plate configured to have the ultrasonic transmission probe installed therein, closely adhered to a surface of the concrete, and configured to transfer the ultrasonic waves of the ultrasonic transmission probe to the concrete, an ultrasonic reception probe configured to detect the ultrasonic waves propagated through the concrete, a second contact plate configured to have the ultrasonic reception probe installed therein, closely adhered to the surface of the concrete, and configured to transfer the ultrasonic waves from the concrete to the ultrasonic reception probe, and a frame configured to have two openings formed therein at an interval, configured to have the first contact plate and the second contact plate inserted into and combined with the respective openings, and assembled into a slip form, in openings formed in the slip form and then closely adhering a bottom of the first contact plate and a bottom of the second contact plate to the surface of the concrete,
• generating the ultrasonic waves of an surface wave form in the concrete C casted in the slip form using the ultrasonic transmission probe,
• detecting the ultrasonic waves of the concrete using the ultrasonic reception probe, converting the detection signal of the ultrasonic reception probe into a digital signal, and calculating a function f(t) for a time of the detection signal of the ultrasonic reception unit,
• calculating a wavelet transform function W(b,a) indicative of a wavelet transform signal for the detection signal of the ultrasonic reception unit by performing a wavelet transform on the detection signal of the ultrasonic reception unit based on an equation:
• W
• 
• (
• b
• ,
• a
• )
• =
• 1
• a
• 
• ∫
• -
• ∞
• +
• ∞
• 
• f
• 
• (
• t
• )
• 
• ψ
• (
• t
• -
• b
• a
• )
• 
• 
• t
• ,
• where
• 
• 
• ψ
• 
• (
• t
• )
• =
• exp
• (
• -
• t
• 2
• 2
• )
• 
• cos
• 
• (
• 5
• 
• t
• )
• ,
• where ‘a’ is a compression coefficient for determining a scale of a wavelet and ‘b’ is a transition coefficient related to a movement in a time axis,
• calculating a time t corresponding to a maximum value of the wavelet transform function W(b,a) and calculating a propagation velocity of the surface wave included in the ultrasonic waves applied to the concrete through the ultrasonic transmission probe by dividing a distance d between the ultrasonic transmission probe and the ultrasonic reception probe by the calculated time t, and
• measuring a strength of the concrete by reading a strength of the concrete corresponding to the calculated propagation velocity of the surface wave from a database in which a relationship between the propagation velocity of the surface wave and the strength of the concrete has been constructed;
• and
• raising the slip form when the measured strength of the concrete becomes predetermined strength which is suitable for raising the slip form or higher.